But when he tells you how to paint, beware! for here he is a perfect will-o'-the-wisp, sparkling out with his lovely lights, and luring you on, now over dry land, now over marsh; giving at times good advice, following it up by bad; telling you practical truths or ethical fallacies. If he was a consistent wrecker, we should get to know his fires and steer clear of them in time; if he was all theory, we should enjoy him as we do other poets; but he is like a man who has built a fine house with chaste design and perfect decoration: it looks all that one can desire, and has only one fault, but that is a grave one--the rafters and supports are _rotten_. He may be justly praising the old muddy Venetian glass, with its ever-varied though clumsily-finished designs, as compared with the sameness of our superior quality and finish; and putting absurdly silly questions into the mouth of his supposed audience, as if a scavenger who does his work honestly and comports himself uprightly could not be as good a gentleman as the aristocrat who paces by him; and making out what is done for economy, and justly so, to be the result of a false shame, forgetting the parable of the talents, or the utility of working the one as well as the five. He may speak of the sanctity of colour, and go on abusing the coarseness of Rubens, or the sensuality of Titian and Correggio, to be perhaps followed up by the information that Titian and Tintoretto, when they looked at a human being, saw the whole of its nature inside and out, and painted it so. He may abuse low tones, and tell us that all which is vile, and deadly, and evil is sombre in colour, although in the same breath he will admit that the tiger-skin is rather pretty, and that some bright flowers and berries are poisonous, and also that there have been lovely women not quite all honey, past and present. He is abusing Salvator Rosa, although comparing him with painters of his time--I don't know why; or in his own graceful way changing his tune, and telling us that all good colour is pensive, and that it is blasphemy to be gay. He may abuse the past painters of storms and gloom, to turn with gloating rapture to the tempests and gloom of Turner. He may remorselessly plunge Teniers into the bottomless abyss for his degrading subjects, yet praise Turner for his wallowing and grovelling amongst the litter of Covent Garden; advocating his slanting steeples as if that were the proper way for steeples to stand, or reviling some one else for the same thing. How he raves throughout his books on the great man! and how the great man, like old Samuel Johnson with his Boswell, must have laughed, when not too much mystified or aggravated, at the high-flown discoveries of his ardent admirer!