_Sensation an internal Affection._--It may even be said of this class of ideas, that their _suggestion_ is of internal origin. The immediate occasion of the mind's having the idea of extension, weight, hardness, color, etc., is not the existence of the object itself, possessing such and such qualities, but the impression produced by the object and its qualities on the sense; in other words, the sensation awakened in us. This it is which awakens and calls forth in the mind the idea of the external object. Were there, for any reason, no sensation, then the objects might exist as now, but we should have no idea of them. But sensation is an internal affection, revealed by consciousness, and the ideas awakened by it and dependent on it, are immediately of internal origin, though mediately dependent on some preceding external condition and occasion. _Ideas of internal Origin._--If we examine, now, the ideas of internal origin, so called, furnished by the faculty of original and intuitive conception, we find that, while they do not directly relate to objects of sense external and material, they nevertheless depend, in like manner, on some preceding operation of sense as the occasion of their development. Observation of what goes on without, or consciousness of what goes on within furnishes the occasion, as all admit, on which these ideas are awakened in the mind. The idea of time, _e. g._, is connected with the succession of events, external or internal--things without and thought and feeling within following each other--which succession is matter of observation or of consciousness. The idea of space is connected with the observation or sensation of body as extended. The idea of beauty and deformity is awakened by the perception of external objects as possessing certain qualities which we thus designate. The idea of right and wrong in like manner connects with something observed in human conduct. So of all ideas of this class. They are not disconnected with, nor independent of, the appropriate objects of observation and consciousness. These objects must exist, these occasions must be furnished, as the _indispensable condition_ of the existence of the idea in the mind. Dispense with the succession of events or the observation of it, and you dispense with the idea of time in the human mind. _Conclusion._--So far as regards the origin of the ideas in question, it is not easy to draw a dividing line, then, between the two classes, marking the one as _external_, the other as _internal_. Both are of external origin, and equally so, in this sense--that they both depend, and equally depend, on some previous exercise of sense as the occasion and condition of their development. Both are of internal origin, in another sense--that they are both awakened in the mind--are both the product of its own activity.