of the senses one by one, saves him the trouble of explaining those which take place between the ideas of different senses at the same time.
The whole of Hartley's system is founded on what seems an entirely gratuitous supposition, viz. the imaginary communication of our ideas to particular places in the brain to correspond not only with the relations of external objects, but with the order of time. This supposition can never be reconciled with the inference mentioned above (to go no farther), that thought is communicated to every part of the thinking substance by an immediate and uniform impulse. For though we should suppose that it is communicated in one manner to what may be called its primary seat, and in another manner over the rest of the brain, yet we shall still be as much at a loss as ever to show a reason why its primary action should always excite the associated or contiguous ideas, while its indirect or secondary action has no power at all to excite any of the ideas, with the spheres of which it necessarily comes in contact in its general diffusion over the whole brain, that is by its simple impulse. This is not all. There is another circumstance which must entirely prevent the least use being made of this distinction, which is that associated ideas are not properly such as are contiguous in place, but such as are connected in point of time, the relation of place not being at all essential to the question, for ideas that have been impressed together are always recollected as parts of the same complex impression, without any regard to the proximity or remoteness of their direct, primary seats in the brain, considered as distinct local impressions. As has been explained above with respect to sounds and visible objects, where the association must evidently arise from what I have called their secondary or relative actions, or, if you will, their conscious ideas,
