A Treatise Concerning the Principles of Human Knowledge

we have first raised a dust and then complain we cannot see.

Philosophy being nothing else but THE STUDY OF WISDOM AND TRUTH

It seems therefore that, to be certain this proposition is universally true, we must either make a particular demonstration for every particular triangle, which is impossible, or once for all demonstrate it of the ABSTRACT IDEA OF A TRIANGLE, in which all the particulars do indifferently partake and by which they are all equally represented.