The Young Soldier It is not death Without hereafter To one in dearth Of life and its laughter, Nor the sweet murder Dealt slow and even Unto the martyr Smiling at heaven: It is the smile Faint as a (waning) myth, Faint, and exceeding small On a boy's murdered mouth.
Biology is a way of approaching the truth about the mind. In biology most people don't tackle problems at the level of complexity that psychoanalysis does. But psychoanalysis has a degree of uncertainty about it. A psychoanalyst may have some deep insights, but cannot, at the moment, run experiments to establish whether it's really the truth.