In the summer of 1857 the Art Treasures Exhibition was held at Manchester, and Ruskin was invited to lecture. The theme he chose was "The Political Economy of Art." He had been studying political economy for some time back, but, as we saw from his letter to Carlyle, he had found no answer in the ordinary text-books for the questions he tried to put. He wanted to know what Bentham and Ricardo and Mill, the great authorities, would advise him as to the best way of employing artists, of educating workmen, of elevating public taste, of regulating patronage; but these subjects were not in their programme. And so he put together his own thoughts into two lectures upon Art considered as Wealth: first, how to get it; next, how to use it.[7] [Footnote 7: July 10 and 13, 1857. He went to Manchester from Oxford, where he had been staying with the Liddells, writing enthusiastically of the beauty of their children and the charm of their domestic life.] There were very few points in these lectures that were not vigorously contested at the moment, and conceded in the sequel--in some form or other. The paternal function of government, the right of the state to interfere in matters beyond its traditional range, its duty with regard to education--all this was quite contrary to the prevailing habits of thought of the time, especially at Manchester, the headquarters of the _laissez faire_ school; but to Ruskin, who, curiously enough, had just then been referring sarcastically to German philosophy, knowing it only at second-hand, and unaware of Hegel's political work--to him this Platonic conception of the state was the only possible one, as it is to most people nowadays. In the same way, his practical advice has been accepted, perhaps unwittingly, by our times. We do now understand the difference between artistic decoration and machine-made wares; we do now try to preserve ancient monuments, and to use art as a means of education. And we are in a fair way, it seems, of lowering the price of modern pictures, as he bids us, to "not more than £500 for an oil picture and £100 for a water-colour." After a visit to the Trevelyans at Wallington he went with his parents to Scotland; for his mother, now beginning to grow old, wanted to revisit the scenes of her youth. They went to the Highlands and as far north as the Bay of Cromarty, and then returned by way of the Abbeys of the Lowlands, to look up Turner sites, as he had done in 1845 on the St. Gothard. From the enjoyment of this holiday he was recalled to London by a letter from Mr. Wornum saying that he could arrange the Turner drawings at the National Gallery.