I know that the doors of the University are being opened to all the newer studies, and that many a student spends most of his time in acquiring the useful knowledge that is to equip him for his profession and for the direct purpose of that profession; knowledge which is to fit him to become lawyer, doctor, minister, engineer, or teacher; yet an Oxford Professor may always maintain the pursuit of Learning for its own sake and keep this purpose before his students even in their most technical work. Now Mineralogy is one of those sciences whose practical applications are clear; it is necessary to the miner and the engineer; indeed, it sprang from their needs; even Crystallography (that is, the study of Crystals), which has always hitherto, though with little reason, been treated for University purposes as a branch of Mineralogy, has also become part of the necessary equipment of the practical chemist and geologist; but both Sciences are, in their general aspects, very far removed from the turmoil of practical life; it is with these aspects that I would fain deal, and especially in relation to the study of crystals. In this connexion, a passage which I quoted from GOETHE fifteen years ago will bear repetition: ‘_There is a flavour_,’ he says, ‘_of the Monk or of the old Bachelor about Crystallography and therefore it is self-sufficient. Practical application in life it has none; its rarest objects, the crystallized precious stones, have to be cut and polished before we can adorn our ladies with them._’ In fact, this lecture, which I was constrained to prepare during a brief holiday in Italy, was written in the midst of surroundings where it was easier to think of Science as cultivated in the quiet of the Laboratory, rather than in the restless scenes of its practical applications, although I am familiar with both. Writing at a window overlooking the mediaeval town and ancient walls of Perugia, with the view of peaceful Assisi and the snowy cap of Monte Subasio across the plain, it was easier to recall the hours of quiet toil and reflection spent in one’s Laboratory at Oxford than visits to Mining Camp, or Metallurgical Works. Accordingly when, under these circumstances, I set about choosing a subject for the present occasion, it occurred to me that I might be allowed to take up my discourse where I laid it down in 1896 and in some sense to continue and conclude the remarks which I then made to the University; and, considering how recently I have left you, I might regard this as my farewell address corresponding to the opening lecture which I then delivered.