An idea of the scholastic discussion of the classification of sciences may be had by following Albertus Magnus’s ponderous approach to a consideration of logic: whether it be a science, and, if so, what place should be allotted it. We draw from the opening of his _liber_ on the _Predicables_,[439] that is to say, his exposition of Porphyry’s Introduction. Albert will consider “what kind of a science (_qualis scientia_) logic may be, and whether it is any part of philosophy; what need there is of it, and what may be its use; then of what it treats, and what are its divisions.” The ancients seem to have disagreed, some saying that logic is no science, since it is rather a _modus_ (mode, manner or method) of every science or branch of knowledge. But these, continues Albertus, have not reflected that although there are many sciences, and each has its special _modus_, yet there is one _modus_ common to all sciences, pertaining to that which is common to them all: the principle, to wit, that through reason’s inquiry, from what is known one arrives at knowledge of the unknown. This mode or method common to every science may be considered in itself, and so may be the subject of a special science. After further balancing of the reasons and authorities _pro_ and _con_, Albertus concludes: “It is therefore clear that logic is a special science just as in ironworking there is the special art of making a hammer, yet its use pertains to everything made by the ironworker’s craft. So this process of discovering the unknown through the known, is something special, and may be studied as a special art and science; yet the use of it pertains to all sciences.” He next considers whether logic is a part of philosophy. Some say no, since there are (as they say) only three divisions of philosophy, physics, mathematics, and metaphysics; others say that logic is a _modus_ of philosophy and not one of its divisions. But, on the contrary, it is shown by others that this view of philosophy omits the practical side, for philosophy’s scope comprehends the truth of everything which man may understand, including the truth of that which is in ourselves, and strives to comprehend both truth and the process of advancing from the known to a knowledge of the unknown. These point out that