Cannery Row is a “kind of nostalgic thing”, according to John Steinbeck. He wrote it, as he explained in a 1953 essay, “for a group of soldiers who said to me: ‘Write something funny that isn’t about the war. Write something for us to read - we’re sick of war.’”

If you like, you can take that statement at face value. First, it is a funny book, funny in a way that hasn’t gone stale in the 70 years since its first publication. Jokes about booze and sex and food tend to have a good shelf life. And Steinbeck’s ribald gags have a perennial joy about them, even when he’s talking about something as antiquated as the Model T: “Two generations of Americans knew more about the Ford coil than the clitoris.”

Similarly, the book is dripping in nostalgia, not to mention sentimentality. Steinbeck clearly loves his central character, marine biologist Doc (who was based on his close friend Ed Ricketts), as much as everyone in the book. As much as poor weak-minded Frankie, whose keening devotion and desire to give the Doc something precious eventually lands him on the wrong side of the law and facing life in an asylum – which we learn in a scene so plangent you can almost hear the swelling strings.

Even when Steinbeck isn’t going full-orchestral there’s a golden glow about Cannery Row, a persistent delight with the world, a continual sense of wistful affection. It’s there in the enthusiastic descriptions of the landscape, and the friendships that have grown up there. In the indulgent lingering passages about the joy of food and drink; the “heartbreaking” smell of a chicken stew cooking on an open fire; and the way a good shot of liquor can leave a character like Mack peering “into his empty glass as though some holy message were written in the bottom”. Even fighting is presented as an enjoyable and healing occupation, a “good”, quick way to settle differences, a “happy” opportunity to flail around with old car parts and a prelude to combatants being “embraced and admired”.

Finally, there is not one mention of the war. But when a book published in 1945 so studiously avoids war, it just makes you wonder about it all the more. Steinbeck isn’t particularly specific about the time frame for his novel, but he does write in the past tense. It’s hard not to think that some time after the book closes, destruction must hit its Edenic setting. How many of its heroes might have found themselves in far more serious fights than those they enjoy in Cannery Row – and how many had to endure rather more than sore heads and comically bust teeth?

But you don’t just have to look outside the novel to find tragedy. For a “funny” novel, Cannery Row is full of sadness. There are three suicides – at least – and the Doc, whom Steinbeck insists is beloved and generous, is also melancholy and lonely, frequently drinking alone at night, listening to delicate, sad music.

The whole book is a complicated metaphor about the richness of life, the way different parts of an ecosystem interact. Just as Doc peers into his tidal pools, Steinbeck’s readers are given a view over a society that is largely cut off from a wider ocean. But we know we are still looking at a place subject to currents and tides, still filled with the same salt water as the rest of the sea.

The strange and dolorous standalone chapters that Steinbeck says he let “crawl in” to his book help form a coherent and fascinating whole. The surface of the novel is so frothy that you may barely notice the deeper currents, its unique and daring structure – but it is there. Far from being the the slight “thing” Steinbeck describes in that essay, or being “trivial” (as it was described by a Times reviewer), Cannery Row actually struck me as very profound.

But just because this novel deserves to be taken seriously, that doesn’t mean it isn’t also as funny as Steinbeck says he intended it to be. As he wrote: “Half a million copies were distributed to troops and they didn’t complain.” How could they?