sufficient to make us associate them together or substitute one for the other. Our thoughts are, as it were, disentangled from the circumstances and consequences which at other times clog their motions: they are let loose, and left at liberty to wander in any direction that chance presents. The greatest singularity observable in dreams is the faculty of holding a dialogue with ourselves, as if we were really and effectually two persons. We make a remark, and then expect the answer, which we are to give ourselves, with the same gravity of attention, and hear it with the same surprise as if it were really spoken by another person. We are played upon by puppets of our own moving. We are staggered in an argument by an unforeseen objection, or alarmed at a sudden piece of information of which we have no apprehension till it seems to proceed from the mouth of some one with whom we fancy ourselves conversing. We have in fact no idea of what the question will be that we put to ourselves, till the moment of its birth. Mr. Locke in treating of our sensations as effects of the impressions of the qualities of things, distinguishes these qualities according to the usual opinion into primary and secondary. The former he considers as really and in themselves the same as they appear to our senses: the other as merely the effects produced by certain objects on the mind and not existing out of it. As this question forms one of the common-places of metaphysical inquiry, I shall give some account of it in his own words. ‘The qualities that are in bodies, rightly considered, are of three sorts. ‘First, The bulk, figure, number, situation, and motion or rest of their solid parts; these are in them whether we perceive them or no; and we have by these an idea of the thing as it is in itself: these I call primary qualities. ‘Secondly, The power that is in any body by reason of its insensible primary qualities to operate after a peculiar manner on any of our senses, and thereby produce in us the different ideas of several colours, sounds, smells, tastes, &c. These are usually called sensible qualities. ‘Thirdly, The power that is in any body, by reason of the particular constitution of its primary qualities, to make such a change in the bulk, figure, texture, and motion of another body, as to make it operate on our senses differently from what it did before. Thus the sun has a power to make wax white, and fire to make lead fluid. These are usually called powers. ‘The first of these, as has been said, I think, may be properly called, real, original, or primary qualities, because they are in the things themselves, whether they are perceived or no: and upon their different modifications it is that the secondary qualities depend. The other two are only powers to act differently upon other things, which powers result from the different modifications of those primary qualities.