There is another disadvantage also in this snatching at successful plays to serve as opera-librettos. Most successful plays nowadays deal with modern life, and they may owe much of their success to the skill with which the dramatist has been able to seize the external aspects of reality. Now, it is an interesting question whether a realistic piece of this sort can ever supply an entirely satisfactory book for an opera, since music is emotional and idealizing. To many persons the opera seems singularly unreal, strangely remote from actual life. Such persons are shocked that Tristan, for instance, should sing for half an hour when he is dying from physical weakness. Tolstoy sided with those who take this attitude, and he had no difficulty in showing up the absurd unreality of an operatic performance, if one insists upon applying to it the standard of our ordinary existence, since we do not burst into song ordinarily to express our every-day desires. Of course, there would be no great difficulty in showing up the absurd unreality of every other art, if the same standard is insisted upon. No art can justify itself for a moment unless we are willing to admit the essential conventions which alone permit it to exist. Tolstoy might as well have pointed out that sculpture is ridiculous, since no human being is ever all of one color, body and clothes, as a statue must be, whether it is made of marble or of bronze. He could have declared that painting is equally untrue to the mere facts of life, since it represents nature absolutely without motion, as when it depicts a field of waving corn which does not really wave but stands fixed forever. If Tolstoy or any one else refuses to accept the conventions of any art, there is no possible reply, except to make it clear to him that he is thereby depriving himself of the delight which that art can give. A departure from the mere fact underlies every art; and it is only because of that departure that the art exists. By convention, that is to say, by tacit agreement between the artist and the public, the artist is allowed to deny certain of the facts of life in order to provide the public with the specific pleasure which only his art can afford.