To understand how the brain works, we first need a list of its parts and some rules for putting them together—in other words, we need a language for the brain. The way that neuroscientists are developing this language is not unlike how a tiny human learns to speak: we first assemble a vocabulary, then add meaning to build a dictionary, and finally develop grammar to link these components together. But mental processes do not come together in an orderly fashion like phrases in a sentence. Instead, brain processes unfold simultaneously as each part of the brain remains at least a little bit engaged at all times. In other words, the language of the brain need not be a linear sentence—it’s more like poetry.