understanding does not, so to speak, meet it half way.

[27] (1) The second mode of perception [i] cannot be said to
give us the idea of the proportion of which we are in search.
(2) Moreover its results are very uncertain and indefinite,
for we shall never discover anything in natural phenomena by its
means, except accidental properties, which are never clearly
understood, unless the essence of the things in question be
known first. (3) Wherefore this mode also must be rejected.

[28] (1) Of the third mode of perception we may say in a manner
that it gives us the idea of the thing sought, and that it
us to draw conclusions without risk of error; yet it is not by
itself sufficient to put us in possession of the perfection we
aim at.

[29] (1) The fourth mode alone apprehends the adequate essence of
a thing without danger of error. (2) This mode, therefore, must be
the one which we chiefly employ. (3) How, then, should we avail
ourselves of it so as to gain the fourth kind of knowledge with
the least delay concerning things previously unknown? (4) I will
proceed to explain.

[30] (1) Now that we know what kind of knowledge is necessary for
us, we must indicate the way and the method whereby we may gain
the said knowledge concerning the things needful to be known.
(2) In order to accomplish this, we must first take care not to
commit ourselves to a search, going back to infinity - that is,
in order to discover the best method of finding truth, there is
no need of another method to discover such method; nor of a third