clear and distinct perceptions, and that our mind is not, like our body, subject to the vicissitudes of circumstance.
clear and distinct perception, or several such together, can be absolutely the cause of another clear and distinct perception. Now, all the clear and distinct perceptions, which we form, can only arise from other clear and distinct perceptions, which are in us; nor do they acknowledge any cause external to us. Hence it follows that the clear and distinct perceptions, which we form, depend solely on our nature, and on its certain and fixed laws; in other words, on our absolute power, not on fortune --that is, not on causes which, although also acting by certain and fixed laws, are yet unknown to us, and alien to our nature and power. As regards other perceptions, I confess that they depend chiefly on fortune. Hence clearly appears, what the true method ought to be like, and what it ought chiefly to consist in --namely, solely in the knowledge of the pure understanding, and its nature and laws. In order that such knowledge may be acquired, it is before all things necessary to distinguish between the understanding and the imagination, or between ideas which are true and the rest, such as the fictitious, the false, the doubtful, and absolutely all which depend solely on the memory. For the understanding of these matters, as far as the method requires, there is no need to know the nature of the mind through its first cause; it is sufficient to put together a short history of the mind, or of perceptions, in the manner taught by Verulam.
Voorburg, 10 June, 1666.
[Note N1]: I. B. has been identified by some with John Bredenburg, a citizen of Rotterdam, who translated into Latin (1675) a Dutch attack on the Tractatus Theologico-Politicus, but the tone of the letter renders this improbable. Murr and Van Vloten think that I. B. may be the physician, John Bresser, who prefixed some verses to the "Principles of Cartesian Philosophy."