 The problem with this position becomes clear when it is considered that Condillac also maintained that colours are extended. In the Essay he claimed that were we to have no other sensations than those of light and colour they would “trace (traceront) extension, lines, and figures before our eyes” so that we would find these ideas to be contained in our sensations (Essay I.i.2. §9). Moreover, this discovery is not an effect of learning or association. Extension and shape are original features possessed by visual sensations, discernible simply by attentive reflection. Someone blind since birth and newly made to see would not originally perceive everything before him as if it were a “point” (i.e., an unextended spot of colour), but would experience “light distributed (répandue) in every direction [outwards as well as above, below, to the left and to the right]” (Essay I.vi. §§12, 14). Condillac continued to retain this view in the Treatise, though with some refinements: Whereas in the Essay he had maintained that colours are extended over all three dimensions, in the Treatise he endorsed the Berkeleyan position that we learn to perceive depth. He also maintained that we do not immediately appreciate that colours are bounded and figured even in two dimensions, but need to learn that they have these features. But he continued to maintain that the colours we originally experience are extended over two dimensions. “Colour presents [offre] extension to the soul that it modifies,” he wrote in the Treatise, “because it is itself extended. This is a fact that cannot be brought into doubt. It is demonstrated by observation” (Treatise I.xi.8). Insofar as colours are extended they must have shapes, even if those shapes are not immediately perceived. The process of learning to perceive shape does not transform our colour sensations and lead them to acquire properties they did not previously have; it merely leads us to discover ones that were there all along. This is the point of claiming that not everything that is necessarily involved with a sensation need be perceived by it.