own juice, and he could not help asking how, if the senses could reveal only ideas of sense, reason was ever able to reveal anything but ideas of reason. Those inferences about the vast world outside, which Leibniz had allowed his spirits to make in their solitary confinement, were reduced by the more scrupulous Kant to scribblings upon their prison walls. These scribblings he officially termed the ideas of pure—that is, of unsupported—reason; but in his private capacity he gently continued to agree with Leibniz and to believe them true.
There was no anomaly, according to Kant, in this situation. An idea might by chance be the image of a reality, but we could never know that it was. For the proof would have to be supplied by a further idea, and would terminate in that. The hypothesis and the corroboration would alike be mental, since experience was of ideas and could envisage nothing but the vicissitudes of the mind.
If you had asked Leibniz what determined the order in which perceptions came into any mind, he would doubtless have answered that the Creator did so, or (translating that symbol into its analytic equivalent in his system) that what did so was the innate destiny or predisposition of that mind to develop in harmony with the best possible universe. Here is a very remarkable unconscious principle of
