In What is Art?, Tolstoy rejects Aestheticism: he does not believe art should be understood in terms of "beauty" or "pleasure." Instead, as he suggests repeatedly, "the chief characteristic of art is the infection of others with the feelings the artist has experience." "True art" is only when the artist expresses a feeling to the viewer/listener/reader. He writes:
"A real work of art destroys, in the consciousness of the receiver, the separation between himself and the artist, nor that alone, but also between himself and all whose minds receive this work of art. In this freeing of our personality from its separation and isolation, in this uniting of it with others, lies the chief characteristic and the great attractive force of art."
Tolstoy also sees a moral thrust to art, and his particular religious sensibilities infuse his view of art. For Tolstoy, art should encourage "the growth of brotherhood among all men--in their loving harmony with one another." He writes a great deal about "Christian art," and so this book is of more interest to one sharing Tolstoy's peculiar Christian view (as I mostly do) than to one who doesn't.
There is much in this book that I do not assent to (I think his definition of art is far, far too narrow, and he thus dismisses anything that doesn't fit his narrow definition). Tolstoy also spends too much time documenting and critiquing aesthetic theories he disagrees with and art he doesn't like ("upper-class art" or "counterfeits of art," he calls it); it is necessary to the book, but as I read the negative (arguments about what isn't art and why) I was mostly looking forward to the positive (arguments about what is art and why).
I primarily assert the prerogative of the individual reader. If I do accept some of Tolstoy's view (for there is still much I do not), it is because I do, not because I think others should. I would rather stand with Tolstoy, demanding meaning in art and seeking its moral purpose, but I don't expect everybody to view art in this way.