And yet here you are, strongly reacting to a philosophical argument made by him.

He's mortal, he's dead, and yet he's affected you here, a throwaway comment on a forum post no one will think about in a week's time.

I didn't think about it that way, thanks!

He also believed in the immortal soul that survives after death, so he may have had a more literal meaning.

A more critical examination of the whole quote makes it clear he was not being that simple.