In his reply, Mr Bailey disavows the impeachment _in toto_. He declares that he never imputed to Berkeley the doctrine, that the eye is not directly percipient of space in the two dimensions of length and breadth. "The perception of this kind of distance," says he, "never formed the subject of controversy with any one ... That we see extension in two dimensions is admitted by all."--(_Letter_, p. 10.) If it can be shown that the doctrine which is here stated to be admitted by all philosophers, is yet expressly controverted by the two metaphysicians whom Mr Bailey appears to have studied most assiduously, it is, at any rate, possible that he may have overlooked, in his own writings, the expression of an opinion which has escaped his penetration in theirs. To convince himself, then, how much he is mistaken in supposing that the visual intuition of longitudinal and lateral extension is admitted by all philosophers, he has but to turn to the works of Dr Brown and the elder Mill. In arguing that we have no immediate perception of visible figure, Dr Brown not only virtually, but expressly, asserts that the sight has no perception of extension in any of its dimensions. Not to multiply quotations, the following will, no doubt, be received as sufficient:--"They (i.e. philosophers) have--_I think without sufficient reason_--universally supposed that the superficial extension of _length and breadth_ becomes known to us by sight originally."[28] Dr Brown then proceeds to argue, with what success we are not at present considering, that our knowledge of extension and figure is derived from another source than the sense of sight. [28] Brown's Lectures, Lecture xxviii.