But Winckelmann might have groped a long time among the multitudes of antique survivals in search of the most valuable objects and those most worthy of his observation, if good fortune had not immediately brought him into contact with Mengs.  The latter, whose own great talent was enthralled by the ancient works of art and especially by such as were beautiful, immediately introduced his friend to the most excellent—­a fact worthy of our attention.  Here Winckelmann learned to recognize beauty of form and its treatment, and was immediately inspired to undertake a treatise, Concerning the Taste of the Greek Artists.  But one cannot go about studying works of art for any length of time without discovering that they are the productions not only of different artists but of different epochs, and that all investigations concerning the place of their origin, their age, their individual merit must be undertaken together.  Winckelmann, with his unerring perception, soon found that this was the axis on which the entire knowledge of art revolves.  He confined himself at first to the most sublime works, which he intended to present in a treatise, Concerning the Style of Sculpture in the Age of Phidias, but he soon rose above these details to the idea of a history of art, and discovered a new Columbus, a land long surmised, hinted at and discussed—­yea, a land, we might say, that had formerly been known and forgotten.

It is sad to observe how at first through the Romans, afterward through the invasion of northern peoples, and the confusion arising in consequence, mankind came into such a state that all true and pure culture was for a long time retarded in its development, indeed was almost made impossible for the entire future.  In any field of art and science that we may contemplate, a direct and unerring perception had already revealed much to the ancient investigator which, during the barbarism which followed, and through the barbaric manner of escaping from barbarism, became and remained a secret; which it will long continue to be for the masses, because the general progress of higher culture in modern times is but slow.  This remark does not apply to technical progress, of which mankind happily makes use without asking questions as to whence it comes and whither it leads.

We are impelled to this observation by certain passages of ancient authors, in which anticipations, even indications, of a possible and necessary history of art appear.  Velleius Paterculus observes with great interest, the coincidence in the rise and fall of all the arts.  As a man of the world, he was especially concerned with the observation that they could be maintained only for a short time at the highest point which it was possible for them to reach.

From his standpoint he could not regard all arts as a living entity [Greek:  (psoon)], which must necessarily reveal an imperceptible beginning, a slow growth, a short and brilliant period of perfection, and a gradual decline—­like every other organic being, except that it is manifested in a number of individuals.  He therefore assigns only moral causes, which certainly must be included as contributory, but hardly satisfy his own great sagacity, because he probably feels that a necessity here exists which cannot be compounded out of detached elements.