object; they will remain separated from each other by intervals which measure, so to speak, the gaps in my needs. It is to fill these intervals that an education of the senses is necessary. The aim of this education is to harmonize my senses with each other, to restore between their data a continuity which has been broken by the discontinuity of the needs of my body, in short to reconstruct, as nearly as may be, the whole of the material object. This, on our hypothesis, explains the need for an education of the senses. Now let us compare it with the preceding explanation. In the first, unextended sensations of sight combine with unextended sensations of touch and of the other senses, to give, by their synthesis, the idea of a material object. But, to begin with, it is not easy to see how these sensations can acquire extension, nor how, above all, when extension in general has been acquired, we can explain in particular the preference of a given one of these sensations for a given point of space. And then we may ask by what happy agreement, in virtue of what pre-established harmony, do these sensations of different kinds co-ordinate themselves to form a stable object, henceforth solidified, common to my experience and to that of all men, subject, in its relation to other objects, to those inflexible rules which we call the laws of nature? In the second, 'the data of our different senses' are, on the contrary, the very qualities of things, perceived first in the things rather than in us:
