for the students, and again for the public. Most of them were eventually published (see Select Bibliography below). He lectured on a wide range of subjects at Oxford, his interpretation of "Art" encompassing almost every conceivable area of study, including wood and metal engraving (Ariadne Florentina), the relation of science to art (The Eagle's Nest) and sculpture (Aratra Pentelici). His lectures ranged through myth, ornithology, geology, nature-study and literature. "The teaching of Art...", Ruskin wrote, "is the teaching of all things." Ruskin was never careful about offending his employer. When he criticised Michelangelo in a lecture in June 1871 it was seen as an attack on the large collection of that artist's work in the Ashmolean Museum. Most controversial, from the point of view of the University authorities, spectators and the national press, was the digging scheme on Ferry Hinksey Road at North Hinksey, near Oxford, instigated by Ruskin in 1874, and continuing into 1875, which involved undergraduates in a road-mending scheme. The scheme was motivated in part by a desire to teach the virtues of wholesome manual labour. Some of the diggers, who included Oscar Wilde, Alfred Milner and Ruskin's future secretary and biographer W. G. Collingwood, were profoundly influenced by the experience: notably Arnold Toynbee, Leonard Montefiore and Alexander Robertson MacEwen. It helped to foster a public service ethic that was later given expression in the university settlements, and was keenly celebrated by the founders of Ruskin Hall, Oxford. In 1879, Ruskin resigned from Oxford, but resumed his Professorship in 1883, only to resign again in 1884. He gave his reason as opposition to vivisection, but he had increasingly been in conflict with the University authorities, who refused to expand his Drawing School. He was also suffering from increasingly poor health. Fors Clavigera and the Whistler libel case In January 1871, the month before Ruskin started to lecture the wealthy undergraduates at Oxford University, he began his series of 96 (monthly) "letters to the workmen and labourers of Great Britain" under the title Fors Clavigera (1871–84). (The letters were published irregularly after the 87th instalment in March 1878.) These letters were personal, dealt with every subject in his oeuvre, and were written in a variety of styles, reflecting his mood and circumstances. From 1873, Ruskin had full control over all his publications, having established George Allen as his sole publisher (see Allen & Unwin). In the July 1877