With that year expired the term for which he had been elected to the Slade Professorship, and in January 1873 he was re-elected. In his first three years he had given five courses of lectures designed to introduce an encyclopædic review and reconstruction of all he had to say upon art. Beginning with general principles, he had proceeded to their application in history, by tracing certain phases of Greek sculpture, and by contrasting the Greek and the Gothic spirit as shown in the treatment of landscape, from which he went on to the study of early engraving. The application of his principles to theory was made in the course on Science and Art ("The Eagle's Nest"). Now, on his re-election, he proceeded to take up these two sides of his subject, and to illustrate this view of the right way to apply science to art, by a course on Birds, in Nature, Art and Mythology, and next year by a study of Alpine forms. The historical side was continued with lectures on Niccola Pisano and early Tuscan sculpture, and in 1874 with an important, though unpublished, course on Florentine Art.
It is to this cycle of lectures that we must look for that matured Ruskinian theory of art which his early works do not reach; and which his writings between 1860 and 1870 do not touch. Though the Oxford lectures are only a fragment of what he ought to have done, they should be sufficient to a careful reader; though their expression is sometimes obscured by diffuse treatment, they contain the root of the matter, thought out for fifteen years since the close of the more brilliant, but less profound, period of "Modern Painters."
The course on Birds[29] was given in the drawing school at the University Galleries. The room was not large enough for the numbers that crowded to hear Professor Ruskin, and each of these lectures, like the previous and the following courses, had to be repeated to a second audience. Great pains had been given to their preparation—much greater than the easy utterance and free treatment of his theme led his hearers to believe. For these lectures and their sequel, published as "Love's Meinie," he collected an enormous number of skins—to compare the plumage and wings of different species; for his work was with the outside aspect and structure of birds, not with their anatomy. He had models made, as large as swords, of the different quill-feathers, to experiment on their action and resistance to the air. He got a valuable series of drawings by H.S. Marks, R.A., and made many careful and beautiful studies himself of feathers and of birds at the Zoological Gardens, and the British Museum; and after all, he had to conclude his work saying, "It has been throughout my trust that if death should write on these, 'What this man began to build, he was not able to finish,' God may also write on them, not in anger, but in aid, 'A stronger than he cometh.'"
Two of the lectures on birds were repeated at Eton[30] before the boys' Literary and Scientific Society and their friends; and between this and 1880 Ruskin often went to address the same audience, with the same interest in young people that had taken him in earlier years to Woolwich.
After a long vacation at Brantwood, the first spent there, he went up to give his course on Early Tuscan Art ("Val d'Arno")[31]. The lectures were printed separately and sold at the conclusion and the first numbers were sent to Carlyle, whose unabated interest in his friend's work was shown in his letter of Oct. 31st: "Perge, perge;—and, as the Irish say, 'more power to your elbow!' I have yet read this 'Val d'Arno' only once. Froude snatched it away from me yesterday; and it has then to go to my brother at Dumfries. After that I shall have it back...."
During that summer and autumn Ruskin suffered from nights of sleeplessness or unnaturally vivid dreams and days of unrest and feverish energy, alternating with intense fatigue. The eighteen lectures in less than six weeks, a "combination of prophecy and play-acting," as Carlyle had called it in his own case, and the unfortunate discussion with an old-fashioned economist who undertook to demolish Ruskinism without understanding it, added to the causes of which we are already aware, brought him to New Year, 1874, in "failing strength, care, and hope." He sought quiet at the seaside, but found modern hotel-life intolerable; he went back to town and tried the pantomimes for distraction,—saw Kate Vaughan in Cinderella, and Violet Cameron in Jack in the Box, over and over again, and found himself:
"Now hopelessly a man of the world!—of that woeful outside one, I mean. It is now Sunday; half-past eleven in the morning. Everybody else is gone to church—and I am left alone with the cat, in the world of sin."
Thinking himself better, he went to Oxford, and announced a course on Alpine form; but after a week was obliged to retreat and go home to Coniston, still hoping to return and give his lectures. But it was no use. The gloom without deepened the gloom within; and he took the wisest course in trying Italy, alone this time with his old servant Crawley.
The greater part of 1874 was spent abroad—first travelling through Savoy and by the Riviera to Assisi, where he wrote to Miss S. Beever:
"The Sacristan gives me my coffee for lunch in his own little cell, looking out on the olive woods; then he tells me stories of conversions and miracles, and then perhaps we go into the sacristy and have a reverent little poke-out of relics. Fancy a great carved cupboard in a vaulted chamber full of most precious things (the box which the Holy Virgin's veil used to be kept in, to begin with), and leave to rummage in it at will! Things that are only shown twice in the year or so, with fumigation! all the congregation on their knees—and the sacristan and I having a great heap of them on the table at once, like a dinner service. I really looked with great respect on St. Francis's old camel-hair dress."