On the other hand, error and suggestion, error and heuristic procedure, since they have in common the practical, extrinsic, and improper combination of ideas, stand in this relation to one another, that the suggestion is not error, but _error always contains in itself willingly or unwillingly a suggestion._ The erring spirit, though without intending it, prepares the material for the search for truth. It means to evade that search or to bring it to an arbitrary end; but in doing so it breaks up the clods of earth, throws them about, ploughs and fertilizes the field where the truth will sprout. Thus it happens that many combinations of ideas, proposed and maintained through caprice and vanity with the lawyer's object of scoring his point, or of shining and astonishing with paradox, or for pastime and for other utilitarian reasons, have been adopted by more serious spirits as steps in the progress of research. The enemies of the truth not only testify to the truth but come to serve it themselves, through the unforeseen consequences of their work. A sort of gratitude comes over us at times and makes us tender toward these adversaries of the truth, because we feel that from them has come the stimulus to obtain it, as from them come the strengthening of our hold upon it and the inspiration, the clear-sightedness, and the warmth of the defence of it that we make against them. [Sidenote: _Individuals and error._] But it is not necessary in yielding to the generous feeling for human fraternity to exaggerate in this last direction. The gratitude that we feel is not deserved by them; at the most, it is God or the universal spirit or Providence who deserves it. They did not wish to serve the truth and did not serve it, save through consequences which are not their work. One-sided and abstract optimism has intruded here also; and perceiving in error the element of suggestion, it has altogether cancelled the category of error in favour of that of suggestion and has pronounced that man always seeks the true, as he always wills the good. Certainly; but there is the man who stops at his individual good, _fruges consumere natus_; and there is the man who progresses to the universal good. There is the man who combines words to give himself and others the illusion of knowing what he does not know and of being able to attend to his own pleasures without further trouble; and there is the man who combines words with anxious soul and spirit intent, _venator medii,_ a hunter of the concept. Here, too, the truth is neither in the optimism nor in the pessimism, but in the doctrine, which conciliates and surpasses them both. Nor does it matter that owing to the defect of abstract optimism that very philosopher, who did more than any other to reveal the hidden richness of the dialectical principle, was not able to look deeply into the problem of error.