"Now, among these ideas, some appear to me to be inborn, others to be foreign and to come from without, and still others to be made and invented by myself. For, as to the faculty of conceiving that which, in general, one calls a thing, or a truth, or a thought, it appears to me that I do not get that from any other source than my own nature; but if now I hear a sound, if I see the sun, if I feel the heat, up to the present I have judged that these sensations proceed from things which exist without me; and lastly, it seems to me that syrens, hippogriffs, and all similar chimeras are fictions and inventions of my mind. But perhaps I can persuade myself, that all these ideas belong to the class of those that I call foreign, and that come to me from without, or that they are all innate, or else that they are all created by myself; for I have not yet clearly discovered their true source. And my chief duty here is to consider, touching those which seem to come from objects without me, what reasons I have for thinking them like their objects. "The first of the reasons is that I seem to be taught to do so by nature; and the second, that I perceive that these ideas are not dependent upon my will; for often they present themselves to me in spite of me, as now, whether I wish it or not, I feel heat, and consequently am persuaded that this sensation or idea of heat is produced in me by something different from me, to wit: by the heat of the fire by which I am sitting. And I cannot see that anything is more reasonable than to judge that this external object emits and impresses upon me its resemblance rather than anything else.