 Consistently with the view that we do not need to learn to perceive depth, Condillac maintained that we do not need to learn to perceive separation in any other spatial dimension. Consequently, a previously blind person, made to see for the first time, should see colours to be extended over all three dimensions. The alternative, in Condillac’s view is that the newly sighted person would experience just a “mathematical point” of colour, and he rejected this as patently absurd (Essay I.vi. §§12–14).