[Man’s] senses do not provide him with automatic knowledge in separate snatches
independent of context, but only with the material of knowledge, which his mind
must learn to integrate. . . . His senses cannot deceive him, . . . physical
objects cannot act without causes, . . . his organs of perception are physical
and have no volition, no power to invent or to distort . . . the evidence they
give him is an absolute, but his mind must learn to understand it, his mind
must discover the nature, the causes, the full context of his sensory material,
his mind must identify the things that he perceives.