Conscious and Unconscious Perception
For Leibniz, the notion of “insensible perceptions” was as useful to psychology as the notion of insensi- ble atoms was to physics. In both cases, what is actu- ally experienced consciously is explained in terms of events beyond the realm of conscious experience. Leibniz (1765/1982) summarized this belief in his law of continuity (not to be confused with the law of contiguity):
Nothing takes place suddenly, and it is one of my great and best confirmed max- ims that nature never makes leaps. I called this the Law of Continuity … There is much work for this law to do in natural science. It implies that any change from small to large, or vice versa, passes through something which is, in respect of degrees as well as of parts, in between; and that no motion ever springs immediately from a state of rest, or passes into one except
Leibniz called perceptions that occurred below the level of awareness petites perceptions (little perceptions). As petites perceptions accumulate, their combined force is eventually enough to cause conscious awareness, or what Leibniz called apper- ception. Therefore, a continuum exists between unconscious sensation and conscious perception. Leibniz was perhaps the first philosopher then to clearly postulate an unconscious mind.
