II. When the definition of the thing has been given, there must
   be no room for doubt as to whether the thing exists or not.
III. It must contain, as far as the mind is concerned, no
   substantives which could be put into an adjectival form;
   in other words, the object defined must not be explained
   through abstractions.
IV. Lastly, though this is not absolutely necessary, it should
   be possible to deduce from the definition all the properties
   of the thing defined.
All these rules become obvious to anyone giving strict
attention to the matter.

[98]  (1) I have also stated that the best basis for drawing a
conclusion is a particular affirmative essence.  (2) The more
specialized the idea is, the more it is distinct, and therefore
clear.  (3) Wherefore a knowledge of particular things should
be sought for as diligently as possible.

[99]  (1) As regards the order of our perceptions, and the manner
in which they should be arranged and united, it is necessary that,
as soon as is possible and rational, we should inquire whether
there be any being (and, if so, what being), that is the cause
of all things, so that its essence, represented in thought, may
be the cause of all our ideas, and then our mind will to the
utmost possible extent reflect nature. (2) For it will possess,
subjectively, nature's essence, order, and union.  (3) Thus we
can see that it is before all things necessary for us to deduce
all our ideas from physical things - that is, from real entities,
proceeding, as far as may be, according to the series of causes,
from one real entity to another real entity, never passing to
universals and abstractions, either for the purpose of deducing
some real entity from them, or deducing them from some real
entity.  (4) Either of these processes interrupts the true
progress of the understanding.

[100]  (1) But it must be observed that, by the series of causes
and real entities, I do not here mean the series of particular
and mutable things, but only the series of fixed and eternal
things. (2) It would be impossible for human infirmity to follow
up the series of particular mutable things, both on account
their multitude, surpassing all calculation, and on account of
the infinitely diverse circumstances surrounding one and the same
thing, any one of which may be the cause of its existence or
non-existence.  (3) Indeed, their existence has no connection
with their essence, or (as we have said already) is not an
eternal truth.

[101] (1) Neither is there any need that we should understand
their series, for the essences of particular mutable things are
not to be gathered from their series or order of existence,
which would furnish us with nothing beyond their extrinsic
denominations, their relations, or, at most, their circumstances,
all of which are very different from their inmost essence.
(101:2) This inmost essence must be sought solely from fixed and
eternal things, and from the laws, inscribed (so to speak) in
those things as in their true codes, according to which all
particular things take place and are arranged; nay, these mutable
particular things depend so intimately and essentially (so to
phrase it) upon the fixed things, that they cannot either be
conceived without them.

[102]  (1) But, though this be so, there seems to be no small
difficulty in arriving at the knowledge of these particular things,
for to conceive them all at once would far surpass the powers of
the human understanding.  (2) The arrangement whereby one thing is
understood, before another, as we have stated, should not be sought
from their series of existence, nor from eternal things.  (3) For
the latter are all by nature simultaneous.  (4) Other aids are
therefore needed besides those employed for understanding eternal
things and their laws.  (5) However, this is not the place to recount
such aids, nor is there any need to do so, until we have acquired a
sufficient knowledge of eternal things and their infallible laws,
and until the nature of our senses has become plain to us.

[103]  (1) Before betaking ourselves to seek knowledge of particular
things, it will be seasonable to speak of such aids, as all tend to
teach us the mode of employing our senses, and to make certain
experiments under fixed rules and arrangements which may suffice to
determine the object of our inquiry, so that we may therefrom infer
what laws of eternal things it has been produced under, and may gain
an insight into its inmost nature, as I will duly show.  (2) Here,
to return to my purpose, I will only endeavor to set forth what seems
necessary for enabling us to attain to knowledge of eternal things,
and to define them under the conditions laid down above.

[104]  (1) With this end, we must bear in mind what has already been
stated, namely, that when the mind devotes itself to any thought, so
as to examine it, and to deduce therefrom in due order all the
legitimate conclusions possible, any falsehood which may lurk in the
thought will be detected; but if the thought be true, the mind will
readily proceed without interruption to deduce truths from it.
(104:2) This, I say, is necessary for our purpose, for our thoughts
may be brought to a close by the absence of a foundation.

[105]  (1) If, therefore, we wish to investigate the first thing of
all, it will be necessary to supply some foundation which may direct
our thoughts thither.  (2) Further, since method is reflective
knowledge, the foundation which must direct our thoughts can be
nothing else than the knowledge of that which constitutes the reality
of truth, and the knowledge of the understanding, its properties, and