For this reason, then, as well as for those previously adduced, if any one agrees with Darwin in holding to the theory of sexual selection notwithstanding this objection from the necessary instability of unuseful embellishments, _a fortiori_ he ought to disregard the objection altogether in its relation to useless specific characters of other kinds. But quite apart from this consideration, which Mr. Wallace and his followers may very properly say does not apply to them, let us see what they themselves have made of the facts of secondary sexual characters--which, of course, are for the most part specific characters--in relation to the doctrine of utility. Mr. Wallace himself, in his last work, quotes approvingly a letter which he received in 1869 from the Rev. O Pickard-Cambridge, as follows:-- "I myself doubt that particular application of the Darwinian theory which attributes male peculiarities of form, structure, colour, and ornament to female appetency or predilection. There is, it seems to me, undoubtedly something in the male organization of a special and sexual nature, which, of its own vital force, develops the remarkable male peculiarities so commonly seen, _and of no imaginable use to that sex_. In as far as these peculiarities show a great vital power, they point out to us the finest and strongest individuals of the sex, and show us which of them would most certainly appropriate to themselves the best and greatest number of females, and leave behind them the strongest and greatest number of progeny. And here would come in, as it appears to me, the proper application of Darwin's theory of Natural Selection; _for the possessors of greatest vital power being those most frequently produced and reproduced, the external signs of it would go on developing in an ever increasing exaggeration_, only to be checked where it became really detrimental in some respect or other to the individual[117]." [117] _Darwinism_, pp.[typo: period missing in scan] 296-7: italics mine.