Classicly

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.