William James, The Principles of Psychology, 1890:
[A]ny number of impressions, from any number of sensory sources, falling simultaneously on a mind WHICH HAS NOT YET EXPERIENCED THEM SEPARATELY, will fuse into a single undivided object for that mind. The law is that all things fuse that can fuse, and nothing separates except what must. [...] Although they separate easier if they come in through distinct nerves, yet distinct nerves are not an unconditional ground of their discrimination, as we shall presently see. The baby, assailed by eyes, ears, nose, skin, and entrails at once, feels it all as one great blooming, buzzing confusion; and to the very end of life, our location of all things in one space is due to the fact that the original extents or bignesses of all the sensations which came to our notice at once, coalesced together into one and the same space. [emphasis original]
Eleanor Rosch et al., "Basic objects in natural categories", Cognitive Psychology 1976:
The world consists of a virtually infinite number of discriminably different stimuli. One of the most basic functions of all organisms is the cutting up of the environment into classifications by which nonidentical stimuli can be treated as equivalent. Yet there has been little explicit attempt to determine the principles by which humans divide up the world in the way that they do. On the contrary, it has been the tendency both in psychology and anthropology to treat that segmentation of the world as originally arbitrary and to focus on such matters as how categories, once given, are learned or the effects of having a label for some segment.
For some related proto- and neo-Whorfian resonances, see "No words, or too many", 1/30/2009.
[h/t Michael Ramscar]