, God had ordained that bodies must
have a circular motion, he would have needed perpetual miracles, or the
ministry of angels, to put this order into execution: for that is contrary
to the nature of motion, whereby the body naturally abandons the circular
line to continue in the tangent straight line if nothing holds it [339]
back. Therefore it is not enough for God to ordain simply that a wound
should excite an agreeable sensation: natural means must be found for that
purpose. The real means whereby God causes the soul to be conscious of what
happens in the body have their origin in the nature of the soul, which
represents the bodies, and is so made beforehand that the representations
which are to spring up one from another within it, by a natural sequence of
thoughts, correspond to the changes in the body.

356. The representation has a natural relation to that which is to be
represented. If God should have the round shape of a body represented by
the idea of a square, that would be an unsuitable representation: for there
would be angles or projections in the representation, while all would be
even and smooth in the original. The representation often suppresses
something in the objects when it is imperfect; but it can add nothing: that
would render it, not more than perfect, but false. Moreover, the
suppression is never complete in our perceptions, and there is in the
representation, confused as it is, more than we see there. Thus there is
reason for supposing that the ideas of heat, cold, colours, etc., also only
represent the small movements carried out in the organs, when one is
conscious of these qualities, although the multiplicity and the diminutive
character of these movements prevents their clear representation. Almost in
the same way it happens that we do not distinguish the blue and the yellow
which play their part in the representation as well as in the composition
of the green, when the microscope shows that what appears to be green is
composed of yellow and blue parts.

357. It is true that the same thing may be represented in different ways;
but there must always be an exact relation between the representation and
the thing, and consequently between the different representations of one
and the same thing. The projections in perspective of the conic sections of
the circle show that one and the same circle may be represented by an
ellipse, a parabola and a hyperbola, and even by another circle, a strai