Modern brain science as we know it began with the work of Santiago Ramón y Cajal, whose creative thought sprang from memories of a childhood spent in the preindustrial Spanish countryside
In the late 19th century most scientists believed the brain was composed of a continuous tangle of fibers as serpentine as a labyrinth. Cajal produced the first clear evidence that the brain is composed of individual cells, later termed neurons, that are fundamentally the same as those that make up the rest of the living world. He believed that neurons served as storage units for mental impressions such as thoughts and sensations, which combined to form our experience of being alive: “To know the brain is equivalent to ascertaining the material course of thought and will,” he wrote. The highest ideal for a biologist, he declared, is to clarify the enigma of the self. In the structure of neurons, Cajal thought he had found the home of consciousness itself.
Cajal is considered the founder of modern neuroscience. Historians have ranked him alongside Darwin and Pasteur as one of the greatest biologists of the 19th century and among Copernicus, Galileo and Newton as one of the greatest scientists of all time. His masterpiece, Texture of the Nervous System of Man and the Vertebrates, is a foundational text for neuroscience, comparable to On the Origin of Species for evolutionary biology. Cajal was awarded the Nobel Prize in 1906 for his work on the structure of neurons, whose birth, growth, decline and death he studied with devotion and even a kind of compassion, almost as though they were human beings. “The mysterious butterflies of the soul,” Cajal called them, “whose beating of wings may one day reveal to us the secrets of the mind.” He produced thousands of drawings of neurons, as beautiful as they are complex, which are still printed in neuroanatomy textbooks and exhibited in art museums. More than 100 years after he received his Nobel Prize, we are indebted to Cajal for our knowledge of what the nervous system looks like. Some scientists even have Cajal’s drawings of neurons tattooed on their bodies. “Only true artists are attracted to science,” he said.
A New Truth
In Cajal’s day, the most advanced method for visualizing cells was histology, an intricate and temperamental process of staining dissected tissue with
