"What leads me to think that the wax exists

Explain the meaning and significance of the following passage in Descartes' overall Cogito argument, from Meditations on First Philosophy: "What leads me to think that the wax exists – namely, that I see it – leads much more obviously to the conclusion that I exist. What I see might not really be the wax; perhaps I don’t even have eyes with which to see anything. But when I see or think I see (I am not here distinguishing the two), it is simply not possible that I who am now thinking am not something. Similarly, that I exist follows from the other bases for judging that the wax exists – that I touch it, that I imagine it, or any other basis, and similarly for my bases for judging that anything else exists outside me. As I came to perceive the wax more distinctly by applying not just sight and touch but other considerations, all this too contributed to my knowing myself even more distinctly, because whatever goes into my perception of the wax or of any other body must do even more to establish the nature of my own mind." Then evaluate and/or criticize the extent to which Descartes argument that "I think, therefore, I am." is indubitable.