Thus there is fixed for us the idea of space as well as of matter. It is a distinct idea; that is, absolute or independent in itself, having no intrinsic connection with phenomena _in_ space. Yet it is got through the senses. How that can be a matter of sensation which is not only not material, but has no connection in itself with matter, Locke does not explain. He thinks it sufficient to say that we see distance between bodies of different color just as plainly as we see the colors. Space is, therefore, a purely immediate idea, containing no more organic relation to intelligence than it has to objects. We get the notion of time as we do that of space, excepting that it is the observation of internal states and not of external objects which furnishes the material of the idea. Time has two elements,--succession and duration. "Observing what passes in the mind, how of our ideas there in train some constantly vanish, and others begin to appear, we come by the idea of succession, and by observing a distance in the parts of this succession we get the idea of duration." Whether, however, time is something essentially empty, having no relation to the events which fill it, as space is essentially empty, without necessary connection with the objects which fill it, is a question Locke does not consider. In fact, the gist of his ideas upon this point is as follows: there is actually an objective space or pure emptiness; employing our senses, we get the idea of this space. There is actually an objective time; employing reflection, we perceive it. There is not the slightest attempt to form a philosophy of them, or to show their function in the construction of an intelligible world, except in the one point of the absolute independence of matter and space. It cannot be said that Leibniz criticises the minor points of Locke in such a way as to throw much light upon them, or that he very fully expresses his own ideas about them. He contents himself with declaring that while the senses may give instances of space, time, and matter, and may suggest to intelligence the stimuli upon which intelligence realizes these notions from itself, they cannot be the source of these notions themselves; finding the evidence of this in the sciences of geometry, arithmetic, and pure physics. For these sciences deal with the notions of space, time, and matter, giving necessary and demonstrative ideas concerning them, which the senses can never legitimate. He further denies the supposed absoluteness or independence of space, matter, and motion. Admitting, indeed, the distinction between extension and matter, he denies that this distinction suffices to prove the existence, or even the possibility, of a vacuum, and ends with a general reference to his doctrine of pre-established harmony, as serving to explain these matters more fully and more accurately.