His inspiration for his work in cognition came while he was a medical student and became seriously ill with tuberculosis. Confined in a sanatorium with very little to read, he spent time reflecting on his condition and the nature of life. What he came to realize was "that what was peculiar to living systems was that they were discrete autonomous entities such that all the processes that they lived, they lived in reference to themselves ... whether a dog bites me or doesn't bite me, it is doing something that has to do with itself." This paradigm of autonomy formed the basis of his studies and work.