The Scientist as Magician
James Clerk Maxwell
“There are three ways of learning props [propositions]—the heart, the head, and the fingers; of these the fingers is the thing for examinations, but it requires constant thought. Nevertheless the fingers have fully better retention of methods than the heart has. The head method requires about a mustard seed of thought, which, of course, is expensive, but then it takes away all anxiety. The heart method is full of anxiety, but dispenses with the thought, and the finger method requires great labor and constant practice, but dispenses with thought and anxiety together.” This is James Clerk Maxwell offering advice, characteristically concise, cryptic, and profound, to his young cousin Charles Cay. We can translate by identifying the fingers as memory and technique, the head as reason, and the heart as intuition.
Maxwell himself was skilled in all three methods. He demonstrated the competence of his fingers as an outstanding student at Cambridge University; and he built his theories by complex reasoning from physical and mathematical models. But the principal source of his genius was his mastery of the heart method. The brilliance of his scientific intuition and insight puts him in a class with Newton and Einstein.
In the construction of his theory of electromagnetism, the main concern in this chapter, Maxwell's intellectual tool was analogy. “In order to obtain physical ideas without adopting a physical theory,” he wrote in the introduction to his first paper on electromagnetism, “we must make ourselves familiar with the existence of physical analogies. By a physical analogy I mean that partial similarity between the laws of one science and those of another which makes each of them illustrate the other.” On the road to his theory of electromagnetism, Maxwell invented two successive mechanical analogies. Neither was a theory: about the first he wrote, “I do not think it contains even a shadow of a true theory.” But in each he intuitively recognized elements of the truth, which he built into his evolving theory. In the end, he took away the mechanical models, like the re-