Note * — Chapter XVIII · On Looking at a Picture

Colours as signs, that is to say even at the most optical and least elaborated stage, have certain very marked spatial characters of their own. Red, for example, seems to advance towards the eye and to swell out of its boundaries, while blue seems to retreat and to withdraw into itself*. Degree of saturation may also give recession in obvious and in more recondite ways. Pure colours in the foreground and greyed colours in the background are a simple example. Similarly opposition of colours is one of the main means by which the stresses and strains of volumes may be suggested.