The Wax. Understanding Change

(P. 120, right column)

I see the wax
     The wax is heated and its properties change
I know that this substance, the wax, remains, with its properties changed.

The various qualities of the wax change and yet the substance remains.
And that substance is known only to my mind
     Properties change but the same thing remains

So, paradoxically!, this argument shows that the mind exists.
     We do not yet have any reason to believe that the wax, or anything in the external world exists

That I can know the wax through its changes shows that the substance my soul exists.

Consider the similar example, p. 121, left column.

I see men on the street
     What I see could be robots wearing hats and coats
I judge that I see men

This judgment shows that my mind (soul) exists

In general, every time I judge, I show that I, the person making the judgment, exists.