Superstition is already on the decline; there would be no more wars if his simple scheme for permanent peace were adopted.

Let the State immediately found Political and Ethical Academies; let the ablest men consecrate their talents to the science of government; and in a hundred years we shall make more progress than we should make in two thousand at the rate we are moving.
If these things are done, human reason will have advanced so far in two or three millenniums that the wisest men of that age will be as far superior to the wisest of to-day as these are to the wisest African savages.

This "perpetual and unlimited augmentation of reason" will one day produce an increase in human happiness which would astonish us more than our own civilisation would astonish the Kaffirs.
4.
The Abbe de Saint-Pierre was indeed terribly at ease in confronting the deepest and most complex problems which challenge the intellect of man.
He had no notion of their depth and complexity, and he lightly essayed them, treating human nature, as if it were an abstraction, by a method which he would doubtless have described as Cartesian.

He was simply operating with the ideas which were all round him in a society saturated with Cartesianism,--supremacy of human reason, progressive enlightenment, the value of this life for its own sake, and the standard of utility.

Given these ideas and the particular bias of his own mind, it required no great ingenuity to advance from the thought of the progress of science to the thought of progress in man's moral nature and his social conditions.