The most extraordinary thing about this extraordinary article still remains to be told.  It was written, we may suppose, between 1757 and 1762, or about that time.  In June, 1756, Diderot wrote to a certain Landois, a fellow-worker on the Encyclopaedia, a letter containing the most emphatic possible repudiation of the whole doctrine of Liberty.  “Liberty is a word void of sense; there are not and there never can have been free beings; we are only what fits in with the general order, with organisation, with education, and with the chain of events.  We can no more conceive a being acting without a motive than we can conceive one of the arms of a balance acting without a weight; and the motive is always exterior and foreign to us, attached either by nature or by some cause or other that is not ourselves. There is only one sort of causes, properly speaking, and those are, physical causes."[188] And so forth in the vein of hard and remorseless necessarianism, which we shall find presently in the pages of the System of Nature.[189]

There is only one explanation of this flagrant contradiction.  Diderot must have written on Liberty just as he wrote on Jesus Christ or the Bible.  He cannot have said what he thought, but only what the persons in authority required him to pretend to think.  We may he sure that a letter to an intimate would be more likely to contain his real opinion than an article published in the Encyclopaedia.  That such mystifications are odious, are shameful, are almost too degrading a price to pay for the gains of such a work, we may all readily enough admit.  All that we can do is to note so flagrant a case, as a striking example of the common artifices of the time.  One other point we may note.  The fervour and dexterity with which Diderot made what he knew to be the worse appear the better cause, make a still more striking example of his astonishing dramatic power of throwing himself, as dialectician, casuist, sophist, into a false and illusive part.

Turning from the philosophical to the political or social group of articles, we find little to add to what has been said in the previous section.  One of the most excellent essays in this group is that on Luxury.  Diderot opens ingeniously with a list of the propositions that state the supposed evils of luxury, and under each proposition he places the most striking case that he can find in history of its falseness.  He goes through the same process with the propositions asserting the gains of luxury to society.  Having thus effectually disposed of any wholesale way of dealing with the subject, he proceeds to make a number of observations on the gains and drawbacks of luxury; these are full of sense and freedom from commonplace.  Such articles as Pouvoir, Souverain, Autorite, do little more than tell over again the old unhistoric story about a society surrendering a portion of its sovereign power to some individual or dynasty to hold in trust.  It is worth remarking