demonstration to demonstration ad infinitum; or else one gains nothing beyond mere words. In fact, it is absolutely necessary that in every word we should perceive directly, and without the assistance of any demonstration, the fundamental notion which it expresses, if we wish to have any foundation to which we may refer our researches, our difficulties, and our personal judgments, whatever in other respects may be the criterion which we adopt, whether we take as our standard the impressions produced on our senses, or the actual impression in general; or whether we cling to the idea by itself, or to any other criterion.
“We must also note carefully the impressions which we receive in the presence of objects, in order to bring ourselves back to that point in the circumstances in which it is necessary to suspend the judgment, or even when the question is about things, the evidence of which is not immediately perceived.
“When these foundations are once laid we may pass to the study of those things,