Here, however, you will raise an objection. Have we not said, on p. 115, that perception is shaped and moulded by nerve-forces that have no mental correlates? and did we not take as an example the casting of perceptions into the forms of ‘thing’ and ‘space’? How, then, can we now speak of perceptions _of_ space?—Well, for one thing, there are various kinds of spatial perception; and it will not do to assume that they are all alike a matter of brain-habit, without mental correlate. Secondly, however, there is a difference between perceiving the piano or the tree _as_ spatial, and turning our attention directly upon its spatial characters, its size or form, its distance or direction. In the latter case, we may rightly speak of a perception of space; we may so speak, even if the various kinds of spatial perception do turn out to be matters of brain-habit; and we must examine every kind for itself, precisely in order to determine how far it is sensory and imaginal, and how far it is a form impressed on sensations and images by the trend of the processes in the brain. So the objection is answered. Coming back to the subject, we note that some of our more =complex perceptions= have a twofold basis: thus the perception of melody is at once qualitative and temporal, and the perception of movement is at once temporal and spatial. Nay more, the perception of a scene, a situation, an event, is threefold: qualitative, temporal and spatial; think of a scene of grand opera, or of an accident on the street. In general, the analysis of these complex perceptions follows from that of the simpler modes, though every one of them has its own psychological problem. It may seem strange that we have not distinguished a group of perceptions based upon sensory =intensity=. The fact is, however, that while intensity enters into all sorts of perceptions (lemonade must not be too sour, the members of a rhythm must be variously accented, a distant sound is faint), it only rarely characterises a perception; and when it does, the perception thus characterised belongs to one or other of the groups already mentioned. We say ‘What a heavy child!’—but the perception of weight, like that of resistance, is itself qualitative. Or we say of a certain composer ‘He always overdoes the drums!’—but the drum-rhythm is itself a temporal perception. _We cannot point, then, to a separate class of intensive perceptions._