Page:Discourse on the method of rightly conducting the reason, and seeking truth in the sciences - Descartes (trans. Veitch).djvu/22

 general doubt. He likewise proceeds to truth through doubt; and that by proposing to determine the limits of doubt. He seeks to discover how far doubt is possible, of what it is impossible; that is, whether there be any knowledge of which we possess an absolute certainty.

Such is the Method of in its prior half. It will be necessary, however, now to develop its application, to show how essays to construct Philosophy, or the Science of Reasons.

Proceeding by Doubt, finds it possible to doubt of the truth of the presentations of Sense, and of the contents of Memory; and likewise even of the demonstrations of Mathematics. Such afford no absolute assurance.

But though it be possible to doubt whether anything exists as it is presented, or existed as represented in Memory, it is impossible to doubt of the existence of the presentations and representations themselves; and as these presentations and representations, in so far as we are conscious of them, are modes of our thought, it is impossible to doubt of the fact of Thought or Thinking.