they produce by their union?

What chiefly gives rise to these objections, and at the same time renders
it so difficult to give a satisfactory answer to them, is the natural
infirmity and unsteadiness both of our imagination and senses, when
employed on such minute objects. Put a spot of ink upon paper, and retire
to such a distance, that the spot becomes altogether invisible; you will
find, that upon your return and nearer approach the spot first becomes
visible by short intervals; and afterwards becomes always visible; and
afterwards acquires only a new force in its colouring without augmenting
its bulk; and afterwards, when it has encreased to such a degree as to be
really extended, it is still difficult for the imagination to break it
into its component parts, because of the uneasiness it finds in the
conception of such a minute object as a single point. This infirmity
affects most of our reasonings on the present subject, and makes it
almost impossible to answer in an intelligible manner, and in proper
expressions, many questions which may arise concerning it.

III. There have been many objections drawn from the mathematics against
the indivisibility of the parts of extension: though at first sight that
science seems rather favourable to the present doctrine; and if it be
contrary in its DEMONSTRATIONS, it is perfectly conformable in its
definitions. My present business then must be to defend the definitions,
and refute the demonstrations.

A surface is DEFINed to be length and breadth without depth: A line to be
length without breadth or depth: A point to be what has neither length,
breadth nor depth. It is evident that all this is perfectly unintelligible
upon any other supposition than that of the. composition of extension by
indivisible points or atoms. How else coued any thing exist without