Should I succeed in showing that the principle which forms the subject of the present inquiry does not issue directly from _one_ primitive notion of our intellect, but rather in the first instance from _various_ ones, it will then follow, that neither can the necessity it brings with it, as a firmly established _à priori_ principle, be _one_ and the _same_ in all cases, but must, on the contrary, be as manifold as the sources of the principle itself. Whoever therefore bases a conclusion upon this principle, incurs the obligation of clearly specifying on which of its grounds of necessity he founds his conclusion and of designating that ground by a special name, such as I am about to suggest. I hope that this may be a step towards promoting greater lucidity and precision in philosophising; for I hold the extreme clearness to be attained by an accurate definition of each single expression to be indispensable to us, as a defence both against error and against intentional deception, and also as a means of securing to ourselves the permanent, unalienable possession of each newly acquired notion within the sphere of philosophy beyond the fear of losing it again on account of any misunderstanding or double meaning which might hereafter be detected. The true philosopher will indeed always seek after light and perspicuity, and will endeavour to resemble a Swiss lake--which through its peacefulness is enabled to unite great depth with great clearness, the depth revealing itself precisely by the clearness--rather than a turbid, impetuous mountain torrent. "_La clarté est la bonne foi des philosophes_," says Vauvenargues. Pseudo-philosophers, on the contrary, use speech, not indeed to conceal their thoughts, as M. de Talleyrand has it, but rather to conceal the absence of them, and are apt to make their readers responsible for the incomprehensibility of their systems, which really proceeds from their own confused thinking. This explains why in certain writers--Schelling, for instance--the tone of instruction so often passes into that of reproach, and frequently the reader is even taken to task beforehand for his assumed inability to understand. § 4. _Importance of the Principle of Sufficient Reason._