with itself.[2] Upon this antithesis between the rational laws of contradiction and sufficient reason—­which, however, is such only for us men, while the divine spirit, which cognizes all things a priori, is able to reduce even the truths of fact to the eternal truths—­Leibnitz bases his distinction between two kinds of necessity.  That is metaphysically necessary whose opposite involves a contradiction; that is morally necessary or contingent which, on account of its fitness, is preferred by God to its (equally conceivable) opposite.  To the latter class belongs, further, the physically necessary:  the necessity of the laws of nature is only a conditional necessity (conditioned by the choice of the best); they are contingent truths or truths of fact.  The principle of sufficient reason holds for efficient as well as for final causes, and between the two realms there is, according to Leibnitz, the most complete correspondence.  In the material world every particular must be explained in a purely mechanical way, but the totality of the laws of nature, the universal mechanism itself, cannot in turn be mechanically explained, but only on the basis of finality, so that the mechanical point of view is comprehended in, and subordinated to, the teleological.  Thus it becomes clear how Leibnitz in the ratio sufficiens has final causes chiefly in mind.

[Footnote 2:  Within the knowledge of reason, as well as in experiential knowledge, a further distinction is made between primary truths (which need no proof) and derived truths.  The highest truths of reason are the identical principles, which are self-evident; from these intuitive truths all others are to be derived by demonstration—­proof is analysis and, as free from contradictions, demonstration.  The primitive truths of experience are the immediate facts of consciousness; whatever is inferred from them is less certain than demonstrative knowledge.  Nevertheless experience is not to be estimated at a low value; it is through it alone that we can assure ourselves of the reality of the objects of thought, while necessary truths guarantee only that a predicate must be ascribed to a subject (e.g., a circle), but make no deliverance as to whether this subject exists or not.]

To the broad and comprehensive tendency which is characteristic of Leibnitz’s thinking, philosophy owes a further series of general laws, which all stand in the closest relation to one another and to his monadological and harmonistic principles, viz., the law of continuity, the law of analogy, the law of the universal dissimilarity of things or of the identity of indiscernibles, and, finally, the law of the conservation of force.