His knowledge of optics was highly remarkable.

He had distinct ideas of perspective, of the projections of the sphere, and of the forms assumed by plane or solid figures in certain positions.

For performing computations he devised a machine of great ingenuity, which also served the purpose, with certain modifications, of representing geometrical diagrams.

In religion he was a sceptic or something more, and in his last hours Diderot supposes him to have engaged in a discussion with a minister of religion, upon the arguments for the existence of a deity drawn from final causes.

This discussion Diderot professes to reproduce, and he makes Saunderson discourse with much eloquence and some pathos.
By one of those mystifications which make the French polemical literature of the eighteenth century the despair of bibliographers, Diderot cites as his authority a _Life of Saunderson_, by Dr.Inchlif.
He sets forth the title with great circumstantiality, but no such book exists or ever did exist.