[49] (1) Let us now return to our proposition. (2) Up to the present, we have, first, defined the end to which we desire to direct all our thoughts; secondly, we have determined the mode of perception best adapted to aid us in attaining our perfection; thirdly, we have discovered the way which our mind should take, in order to make a good beginning--namely, that it should use every true idea as a standard in pursuing its inquiries according to fixed rules. (49:3) Now, in order that it may thus proceed, our method must furnish us, first, with a means of distinguishing a true idea from all other perceptions, and enabling the mind to avoid the latter; secondly, with rules for perceiving unknown things according to the standard of the true idea; thirdly, with an order which enables us to avoid useless labor. (49:4) When we became acquainted with this method, we saw that, fourthly, it would be perfect when we had attained to the idea of the absolutely perfect Being. (5) This is an observation which should be made at the outset, in order that we may arrive at the knowledge of such a being more quickly. [50] (1) Let us then make a beginning with the first part of the method, which is, as we have said, to distinguish and separate the true idea from other perceptions, and to keep the mind from confusing with true ideas those which are false, fictitious, and doubtful. (2) I intend to dwell on this point at length, partly to keep a distinction so necessary before the reader's mind, and also because there are some who doubt of true ideas, through not having attended to the distinction between a true perception and all others. (3) Such persons are like men who, while they are awake, doubt not that they are awake, but afterwards in a dream, as often happens, thinking that they are surely awake, and then finding that they were in error, become doubtful even of being awake. (4) This state of mind arises through neglect of the distinction between sleeping and waking. [51] (1) Meanwhile, I give warning that I shall not here give essence of every perception, and explain it through its proximate cause. (2) Such work lies in the province of philosophy. (3) I shall confine myself to what concerns method--that is, to the character of fictitious, false and doubtful perceptions, and the means of freeing ourselves therefrom. (4) Let us then first inquire into the nature of a fictitious idea.