The Preliminary Discourse to the Encyclopaedia, of which by far the greater and more valuable portion was written by D'Alembert, contains a fine survey of the progress of science, thought, and letters since the revival of learning.

It is a generous canonisation of the great heroes of secular knowledge.

It is rapid, but the contributions of Bacon, Descartes, Newton, Locke, Leibnitz are thrown into a series that penetrates the reader's mind with the idea of ordered growth and measured progress.

This excited a vivid hopefulness of interest, which insensibly but most effectually pressed the sterile propositions of dogmatic theology into a dim and squalid background.

Nor was this all.
The Preliminary Discourse and the host of articles marshalled behind it, showed that the triumphs of knowledge and true opinion had all been gained on two conditions.