[79] (1) Hence we cannot cast doubt on true ideas by the supposition that there is a deceitful Deity, who leads us astray even in what is most certain. (2) We can only hold such an hypothesis so long as we have no clear and distinct idea--in other words, until we reflect the knowledge which we have of the first principle of all things, and find that which teaches us that God is not a deceiver, and until we know this with the same certainty as we know from reflecting on the are equal to two right angles. (3) But if we have a knowledge of God equal to that which we have of a triangle, all doubt is removed. (79:4) In the same way as we can arrive at the said knowledge of a triangle, though not absolutely sure that there is not some arch-deceiver leading us astray, so can we come to a like knowledge of God under the like condition, and when we have attained to it, it is sufficient, as I said before, to remove every doubt which we can possess concerning clear and distinct ideas. [80] (1) Thus, if a man proceeded with our investigations in due order, inquiring first into those things which should first be inquired into, never passing over a link in the chain of association, and with knowledge how to define his questions before seeking to answer them, he will never have any ideas save such as are very certain, or, in other words, clear and distinct; for doubt is only a suspension of the spirit concerning some affirmation or negation which it would pronounce upon unhesitatingly if it were not in ignorance of something, without which the knowledge of the matter in hand must needs be imperfect. (2) We may, therefore, conclude that doubt always proceeds from want of due order in investigation. [81] (1) These are the points I promised to discuss in the first part of my treatise on method. (2) However, in order not to omit anything which can conduce to the knowledge of the understanding and its faculties, I will add a few words on the subject of memory and forgetfulness. (81:3) The point most worthy of attention is, that memory is strengthened both with and without the aid of the understanding. (4) For the more intelligible a thing is, the more easily is it remembered, and the less intelligible it is, the more easily do we forget it. (5) For instance, a number of unconnected words is much more difficult to remember than the same number in the form of a narration.