Several murders committed here since I came, and more attempted; one by a brother on his sister, in the house where I lay." March 22 (N.S.): "The new philosophy of Des Cartes prohibited to be taught in universities, schools, and academies." It is plain from the journal that Locke's mind was now busy with the class of questions which were afterwards treated in the Essay: reflections on space, the extent of possible knowledge, the objects and modes of study, etc., being curiously interspersed with his notes of travel. In respect of health, he does not seem to have benefited much by his stay at Montpellier, which, as before stated, he left in the early spring of 1677. By slow stages he travelled to Paris, where he joined a pupil, the son of Sir John Banks, who had been commended to his supervision by Shaftesbury. This tutorial engagement lasted for nearly two years, and, in consequence of it, Locke remained in France longer than he had originally intended. In a letter written to his old friend Mapletoft from Paris in June, 1677, after some playful allusions to Mapletoft's love affairs, he says:--"My health is the only mistress I have a long time courted, and is so coy a one that I think it will take up the remainder of my days to obtain her good graces and keep her in good humour." There can be no question that, at this time, the state of his health was a matter of very serious concern to him, and it may possibly have been the cause of his not marrying. While in Paris he probably took a pretty complete holiday, seeing the sights, however, making occasional excursions, forming new acquaintances, and exercising a general supervision over the education of his young charge.