The second objection is derived from the necessity there would be of PENETRATION, if extension consisted of mathematical points.

A simple and indivisible atom, that touches another, must necessarily penetrate it; for it is impossible it can touch it by its external parts, from the very supposition of its perfect simplicity, which excludes all parts.

It must therefore touch it intimately, and in its whole essence, SECUNDUM SE, TOTA, ET TOTALITER; which is the very definition of penetration.
But penetration is impossible: Mathematical points are of consequence equally impossible.
I answer this objection by substituting a juster idea of penetration.
Suppose two bodies containing no void within their circumference, to approach each other, and to unite in such a manner that the body, which results from their union, is no more extended than either of them; it is this we must mean when we talk of penetration.

But it is evident this penetration is nothing but the annihilation of one of these bodies, and the preservation of the other, without our being able to distinguish particularly which is preserved and which annihilated.

Before the approach we have the idea of two bodies.