In short, progress exists, but not all along the line. As thought travels slowly in its own domain, so mental science is behindhand. A true idea is not mechanically reproduced, it must be tended for it to bear fruit, but what tendance would avail, if it is only with difficulty that we discriminate between what we know already, and what we do not yet know, for this distinction must accompany conscious progress.
Everything around us tends to keep us in this penumbra, which is so favourable to inertia, ignorance, sleep. Certain groups of philosophical ideas become condensed and systematised; in some systems there are one or two great thoughts only. This suffices--these systems remain, germinate and direct contemporaneous generations as well as those of the future. It may also happen that these same ideas invade brains little prepared to receive them, and thus deviate from their course, err as they advance, and end by becoming so travestied that it is no longer possible to know what they were at their origin--a swerving movement has taken place, which causes suffering to contemporaries, and, still more, to those who come after. Thus the bulk increases, the bulk of truth and the bulk of error; and this fatal expansion of the true and the false, intertwined the one with the other, pursues its encroaching and troublous way.
This confusion is something impersonal; it is an opaque body which interposes itself between the truth and ourselves, and prevents us from contemplating it; but the confusion may also arise directly from those whose mission it is to guide us. I open a book written by some grave thinker who, I imagine, knows his subject thoroughly, and I begin to read in all confidence; at first I think I understand him; then I am stopped by a word, and I wonder what meaning the author has attached to it; a little further I come upon the same word, which now seems invested with another signification; this disconcerts me, and I close the book. I take another, but the same disagreeable surprise awaits me, and I find everywhere terms whose meaning varies to suit the convenience of the author; and what we are to understand by these words is nowhere explained. These defects arise probably from the fact that certain philosophers, taking their confused opinions for new ideas, seek for words in which to express them, and not finding them in their vocabulary, they coin them, using terms to which no precise meaning is attached; which terms remain more or less enigmatical to the authors themselves, and, consequently, unintelligible to the readers; in this way does the confusion of ideas arise and is propagated. A philosopher, I think it was Haman, made the following very true and very alarming statement: “Language is not only the basis of our power of thought, but also the point from which our misunderstandings and errors spring”; and Hobbes also says: “It is obvious that truth and falsehood dwell only with those living creatures who have the use of speech.”