division between the living

Finding himself at loose ends after the war, he decided the most interesting research problem lay in trying to understand the physical basis of life, the division between the living and the nonliving.

Summoning what Ridley calls "the bravado of a bankrupt gambler with no high cards left," Crick changed fields in his 30's, to study "the division between the living and nonliving," and landed in Cambridge in 1947, where he met Watson four years later.