The question "Has a man in general the right to kill himself?" is incorrectly put. There can be no question of "right". If he is able to do it, then he has the right. I think that the possibility of killing oneself is a safety-valve. Having it, man has no right (here the expression "right" is appropriate) to say that life is unbearable.Tolstoy's view--essentially insufferable--is of course predicated on a belief that the Universe is purposive and that therefore one's own insignificant life has a purpose as well, a view that many of us living more than a century later have a hard time countenancing.
If it were impossible to live, then one would kill oneself; and consequently one cannot speak of life as being unbearable. The possibility of killing himself has been given to man, and therefore he may (he has the right to) kill himself, and he continually uses this right - when he kills himself in duels, in war, by dissipation, wine, tobacco, opium, etc.
The question can only be as to whether it is reasonable and moral (the reasonable and moral always coincide) to kill oneself. No, it is unreasonable; as unreasonable as to cut off the shoots of a plant which one wishes to destroy; it will not die, but will merely grow irregularly..
Life is indestructible; it is beyond time and space, therefore death can only change its form, arrest its manifestation in this world. But having arrested it in this world, I, first, do not know whether its manifestation in another world will be more pleasant to me; and, secondly, I deprive myself of the possibility of experiencing and acquiring by my ego all that could be acquired in this world.
Besides this, and above all, it is unreasonable because by arresting my life owing to its apparent unpleasantness, I hereby show that I have a perverted idea of the object of my life, assuming that its object is my pleasure - whereas its objects, on the other hand, personal perfection, and on the other, the service of that work which is being accomplished by the whole life of the Universe.
It is for the same reason that suicide is also immoral. Life in its entirety, and the possibility of living until natural death, have been given to man only on the condition that he serve the life of the Universe. But, having profited by life so long as it was pleasant, he refuses to serve the Universe as soon as life becomes unpleasant: whereas, in all probability, his service commenced precisely when life began to appear unpleasant. All work appears at first unpleasant.
In the Optin Monastery, for more than thirty years, there lay on the floor a monk smitten with paralysis, who had the use of his left hand only. The doctors said that he was sure to suffer much, but not only did he refrain from complaining of his position, but incessantly making the sign of the cross, and looking at the ikons, he smilingly expressed his gratitude to God and joy in that spark of life which flickered in him. Tens of thousands of visitors came to see him, and it is difficult to imagine all the good which flowed into the world through this man, though deprived of the possibility of any activity. Certainly he did more good than thousands and thousands of healthy people who imagine that in various institutions they are serving the world.
While there is life in man, he can perfect himself and serve the Universe. But he can serve the Universe only be perfecting himself, and perfect himself only by serving the Universe.
Chekhov--remaining, like Tolstoy, largely in character--offers a different spin, focusing on the inability of our art to grasp the dimensions of self-destruction:
The suicide of a seventeen-year-old boy is a very promising and tempting theme, but a frightening one to undertake. An issue so painful to us all calls for a painfully forceful response, and do we young writers have the inner resources for it? No. When you guarantee the success of this theme, you are judging by your own standards. But then, in addition to talent, the men of your generation had erudition, schooling, iron and phosphorus, while contemporary talents have nothing of the sort. Frankly speaking, there is reason to rejoice that they keep away from serious problems. Let them have a go at your seventeen-year-old, and I am certain that X, completely unaware of what he is doing, will slander him and pile lie upon blasphemy with the purest of intentions; Y will give him a shot of pallid and petty tendentiousness; while Z will explain away the suicide as a psychosis. Your boy is of a good, pure nature. He seeks after God. He is loving, sensitive and deeply hurt. To handle a figure like that, an author has to be capable of suffering, while all our contemporary authors can do is whine and snivel.The sections of Infinite Jest dealing with Kate Gompert's suicidal depression are among the most memorable and powerful in the book; like Tolstoy in Anna Karenina, David Foster Wallace wrote about depression and the suicidal impulse with the clarity and force of someone who had experienced them. Yet I almost off-handedly assumed that a person who found the very stuff of the world as fascinating as he obviously did would have a handle, a power, an ability to overcome the darkness that has claimed so many. Intellectually, I knew that depression doesn't work that way, but the joy I am fortunate enough to take in the dailiness of life has always made it extremely difficult for me to imagine its obverse.
I find myself thinking about Malcolm Lowry--who, if he didn't explicitly kill himself, at least registered, again and again, his dissatisfaction and discomfort with the state of being alive. In a letter to his wife's family, he wrote that the theme of his novel of extended suicide, Under the Volcano, was that "only against death does man cry out in vain."
Rest in peace, David Foster Wallace. Our thoughts are with your family and friends.