Take Julian Huxley's phrase 'the repressive mechanisms of the unconscious'. Here 'the unconscious' is an entity. Mach would therefore remind us that it is a compendious mental symbol for a group of sensations. What are these sensations? and are we quite sure that they warrant us giving independent status to the entity? Further, in applying such a phrase as repressive mechanisms to an aspect of mental activity, a metaphor is used which passes from mind to matter with a facility which somewhat disquiets me. The disquiet becomes bewilderment when I read that energies can be locked up, or released fi'om their grapplings, and that vital human impulses can be dead-locked by misguided repressive super-egos. Even 'blind decontrol' is metaphorical, though perhaps not quite as metaphorical as 'blind automatic repression'. When Waddington, commenting on Engels, writes of 'unrestrained biological drives' in connection with 'the imperativeness of the socially determined Good' he does not, to my thinking, bring light to our darkness.