It is mortifying enough to write,—but I think thus much ought to be written,—concerning myself, as 'the author of Modern Painters.' In three months I shall be fifty years old: and I don't at this hour—ten o'clock in the morning of the two hundred and sixty-eighth day of my forty-ninth year—know what 'moss' is. There is nothing I have more intended to know—some day or other. But the moss 'would always be there'; and then it was so beautiful, and so difficult to examine, that one could only do it in some quite separated time of happy leisure—which came not. I never was like to have less leisure than now, but I will know what moss is, if possible, forthwith.