“Principles are good and worth the effort only when they develop into deeds,” Van Gogh wrote to his brother in a beautiful letter about talking vs. doing and the human pursuit of greatness. “The great doesn’t happen through impulse alone, and is a succession of little things that are brought together.” But what stands between the impulse for greatness and the doing of the “little things” out of which success is woven?

That’s what neuroscience founding father Santiago Ramón y Cajal (May 1, 1852–October 17, 1934) addresses in his 1897 book Advice for a Young Investigator (public library) — the science counterpart to Rilke’s Letters to a Young Poet and Anna Deavere Smith’s Letters to a Young Artist, predating one by nearly a decade and the other by more than a century.

Although Cajal’s counsel is aimed at young scientists, it is replete with wisdom that applies as much to science as it does to any other intellectually and creatively ambitious endeavor — nowhere more so than in one of the pieces in the volume, titled “Diseases of the Will,” presenting a taxonomy of the “ethical weaknesses and intellectual poverty” that keep even the most gifted young people from ascending to greatness.

It should be noted that Cajal addresses his advice to young men, on the presumption that scientists are male — proof that even the most visionary geniuses are still products of their time and place, and can’t fully escape the limitations and biases of their respective era, or as Virginia Woolf memorably put it in Orlando, “It is probable that the human spirit has its place in time assigned to it.” (Lest we forget, although the word “scientist” had been coined for a woman half a century earlier, women were not yet able to vote and were decades away from being admitted into European universities, so scientists in the strict academic sense were indeed exclusively male in Cajal’s culture.) Still, when stripped of its genderedness, his advice remains immensely psychologically insightful, offering a timeless corrective for the pitfalls that keep talent and drive from manifesting into greatness, not only in science but in any field.

Considering the all too pervasive paradox of creative people “who are wonderfully talented and full of energy and initiative [but] who never produce any original work and almost never write anything,” Cajal divides them into six classes according to the “diseases of the will” afflicting them — contemplators, bibliophiles and polyglots, megalomaniacs, instrument addicts, misfits, and theorists.

He examines the superficiality driving the “particularly morbid variety” of the first type:

[Contemplators] love the study of nature but only for its aesthetic qualities — the sublime spectacles, the beautiful forms, the splendid colors, and the graceful structures.

With an eye to his own chosen field of histology, which he revolutionized by using beauty to illuminate the workings of the brain, Cajal notes that a contemplator will master the finest artistic techniques “without ever feeling the slightest temptation to apply them to a new problem, or to the solution of a hotly contested issue.” He adds:

[Contemplators] are as likable for their juvenile enthusiasm and piquant and winning speech as they are ineffective in making any real scientific progress.

More than a century before Tom Wolfe’s admonition against the rise of the pseudo-intellectual, Cajal treats with special disdain the bibliophiles and polyglots — those who use erudition not as a tool of furthering humanity’s enlightenment but as a personal intellectual ornament of pretension and vanity. He diagnoses this particular “disease of the will”:

The symptoms of this disease include encyclopedic tendencies; the mastery of numerous languages, some totally useless; exclusive subscription to highly specialized journals; the acquisition of all the latest books to appear in the bookseller’s showcases; assiduous reading of everything that is important to know, especially when it interests very few; unconquerable laziness where writing is concerned; and an aversion to the seminar and laboratory.

In a passage that calls to mind Portlandia’s irrepressibly hilarious “Did You Read It?” sketch, he writes:

Naturally, our bookworm lives in and for his library, which is monumental and overflowing. There he receives his following, charming them with pleasant, sparkling, and varied conversation — usually begun with a question something like: “Have you read So-and-so’s book? (An American, German, Russian, or Scandinavian name is inserted here.) Are you acquainted with Such-and-such’s surprising theory?” And without listening to the reply, the erudite one expounds with warm eloquence some wild and audacious proposal with no basis in reality and endurable only in the context of a chat about spiritual matters.

Cajal examines the central snag of these vain pseudo-scholars:

Discussing everything — squandering and misusing their keen intellects — these indolent men of science ignore a very simple and very human fact… They seem only vaguely aware at best of the well-known platitude that erudition has very little value when it does not reflect the preparation and results of sustained personal achievement. All of the bibliophile’s fondest hopes are concentrated on projecting an image of genius infused with culture. He never stops to think that only the most inspired effort can liberate the scholar from oblivion and injustice.

Three decades before John Cowper Powys’s incisive dichotomy between being educated and being cultured, Cajal is careful to affirm the indisputable value of learnedness put to fertile use — something categorically different from erudition as a personal conceit:

No one would deny the fact that he who knows and acts is the one who counts, not he who knows and falls asleep. We render a tribute of respect to those who add original work to a library, and withhold it from those who carry a library around in their head. If one is to become a mere phonograph, it is hardly worth the effort of complicating cerebral organization with study and reflection. Our neurons must be used for more substantial things. Not only to know but also to transform knowledge; not only to experience but also to construct. […] The eloquent fount of erudition may undoubtedly receive enthusiastic plaudits throughout life in the warm intimacy of social gatherings, but he waits in vain for acclamation from the great theater of the world. The wise man’s public lives far away, or does not yet exist; it reads instead of listens; it is so austere and correct that recognition with gratitude and respect is only extended to new facts that are placed in circulation on the cultural market.

Next come the megalomaniacs, who may be talented and motivated, but are bedeviled by a deadly overconfidence that ultimately renders them careless and unrigorous in their work. Cajal writes:

People with this type of failure are characterized by noble and winning traits. They study a great deal, but love personal activities as well. They worship action and have mastered the techniques needed for their research. They are filled with sincere patriotism and long for the personal and national fame that comes with admirable conquests. Yet their eagerness is rendered sterile by a fatal flaw. While they are confirmed gradualists in theory, they turn out to rely on luck in practice. As if believing in miracles, they want to start their careers with an extraordinary achievement. Perhaps they recall that Hertz, Mayer, Schwann, Roentgen, and Curie began their scientific careers with a great discovery, and aspire to jump from foot soldier to general in their first battle. They end up spending their lives planning and plotting, constructing and correcting, always submerged in feverish activity, always revising, hatching the great embryonic work—the outstanding, sweeping contribution. And, as the years go, by expectation fades, rivals whisper, and friends stretch their imaginations to justify the great man’s silence. Meanwhile, important monographs are raining down abroad on the subjects they have so painstakingly explored, fondled, and worn to a thread.

Cajal reflects on the only remedy for the megalomaniac’s main stumbling block:

All of this happens because when they started out these men did not follow with humility and modesty a law of nature that is the essence of good sense: Tackle small problems first, so that if success smiles and strength increases one may then undertake the great feats of investigation.

He considers a special class of megalomaniac — the serial ideator who always fails to reach the stage of execution and whose rampant dreaming chronically falls short of doing. (This type, it occurs to me, has an analog in love — the serial besotter, who thrives on the thrill of infatuation, but crumbles as soon as the fantasy the beloved becomes a real relationship teeming with imperfection and the often toilsome work of love.) Cajal writes:

The dreamers who are reminiscent of the conversationalists of old might be seen as a variety of megalomaniac. They are easily distinguished by their effervescence and by a profusion of ideas and plans of attack. Their optimistic eyes see everything through rose-colored glasses. They are confident that, once accepted, fruits of their initiative will open broad horizons in science, and yield invaluable practical results as well. There is only one minor drawback, which is deplorable — none of their undertakings are ever completed. All come to an untimely end, sometimes through lack of resources, and sometimes through lack of a proper environment, but usually because there were not enough able assistants to carry out the great work, or because certain organizations or governments were not sufficiently civilized and enlightened to encourage and fund it. The truth is that dreamers do not work hard enough; they lack perseverance.

He turns to the instrument addicts next — a class particularly prominent in our present culture of techno-fetishism. In a sentiment that applies with astonishing precision to today’s legions of failed serial entrepreneurs — the foundering founders who have fetishized the glitzy sleekness of an invention, be it a gadget or an app, over its core conceptual value proposition — Cajal writes:

This rather unimportant variety of ineffectualist can be recognized immediately by a sort of fetishistic worship of research instruments. They are as fascinated by the gleam of metal as the lark is with its own reflection in a mirror. […] Cold-hearted instrument addicts cannot make themselves useful. They suffer from an almost incurable disease, especially when it is associated (as it commonly is) with a distinctive moral condition that is rarely admitted — a selfish and disagreeable obsession with preventing others from working because they personally do not know how, or don’t want, to work.

Next, Cajal turns to the misfit — though I suspect the word could have been translated better, for he doesn’t mean the visionary nonconformist who propels society forward but the person who has ended up in a vocation or environment ill-fitted to their inherent talents, thwarting them from reaching their potential. He writes:

Instead of being abnormal, misfits are simply unfortunate individuals who have had work unsuited to their natural aptitudes imposed on them by adverse circumstances. When everything is said and done, however, these failures still fall in the category of abulics because they lack the energy to change their course, and in the end fail to reconcile calling and profession. It appears to us that misfits are hopelessly ill. On the other hand, this certainly does not apply to the young men whose course has been swayed by family pressure or the tyrannies of their social environment, and who thus find themselves bound to a line of work by force. With their minds still flexible, they would do well to change course as soon as favorable winds blow. Even those toiling in a branch of science they do not enjoy — living as if banished from the beloved country of their ideals — can redeem themselves and work productively. They must generate the determination to reach for lofty goals, to seek an agreeable line of work — which suits their talents — that they can do well and to which they can devote a great deal of energy. Is there any branch of science that lacks at least one delightful oasis where one’s intellect can find useful employment and complete satisfaction?

Next come the theorists. Marked by “a certain flaunting of intellectual superiority that is only pardoned in the savant renowned for a long series of true discoveries,” the theorist becomes so besotted with her ideas and hypotheses that she shirks from testing them against reality and instead continually narrows her lens to only factor in what supports her theories. Cajal writes:

There are highly cultivated, wonderfully endowed minds whose wills suffer from a particular form of lethargy, which is all the more serious because it is not apparent to them and is usually not thought of as being particularly important. Its undeniable symptoms include a facility for exposition, a creative and restless imagination, an aversion to the laboratory, and an indomitable dislike for concrete science and seemingly unimportant data. They claim to view things on a grand scale; they live in the clouds. They prefer the book to the monograph, brilliant and audacious hypotheses to classic but sound concepts. When faced with a difficult problem, they feel an irresistible urge to formulate a theory rather than to question nature. As soon as they happen to notice a slight, half-hidden, analogy between two phenomena, or succeed in fitting some new data or other into the framework of a general theory –whether true or false — they dance for joy and genuinely believe that they are the most admirable of reformers. The method is legitimate in principle, but they abuse it by falling into the pit of viewing things from a single perspective. The essential thing for them is the beauty of the concept. It matters very little whether the concept itself is based on thin air, so long as it is beautiful and ingenious, well-thought-out and symmetrical.

Exclaiming that “so many apparently immutable doctrines have fallen,” Cajal summarizes this particular pitfall rather bluntly:

Basically, the theorist is a lazy person masquerading as a diligent one. He unconsciously obeys the law of minimum effort because it is easier to fashion a theory than to discover a phenomenon.

Cajal takes care to note that while hypotheses have their use “as inspiration during the planning stage of an investigation, and for stimulating new fields of investigation,” the theorist’s mistake is a blind attachment to her theories not as a means to truth but as an end of intellectual labor:

One must distinguish between working hypotheses … and scientific theories. The hypothesis is an interpretative questioning of nature. It is an integral part of the investigation because it forms the initial phase, the virtually required antecedent. But to speculate continuously — to theorize just for its own sake, without arriving at an objective analysis of phenomena — is to lose oneself in a kind of philosophical idealism without a solid foundation, to turn one’s back on reality. Let us emphasize again this obvious conclusion: a scholar’s positive contribution is measured by the sum of the original data that he contributes. Hypotheses come and go but data remain. Theories desert us, while data defend us. They are our true resources, our real estate, and our best pedigree. In the eternal shifting of things, only they will save us from the ravages of time and from the forgetfulness or injustice of men. To risk everything on the success of one idea is to forget that every fifteen or twenty years theories are replaced or revised. So many apparently conclusive theories in physics, chemistry, geology, and biology have collapsed in the last few decades! On the other hand, the well-established facts of anatomy and physiology and of chemistry and geology, and the laws and equations of astronomy and physics remain — immutable and defying criticism.

Advice for a Young Investigator is a marvelous read in its totality, exploring such aspects of science and success as the art of concentration, the most common mistakes beginners make, the optimal social and cultural conditions for discovery, and how to avoid the perilous trap of prestige. Complement it with physicist and writer Alan Lightman on the shared psychology of creative breakthrough in art and science, philosopher Arthur Schopenhauer on the crucial difference between genius and talent, and astrophysicist and writer Janna Levin on the animating force of great scientists.