Rules cannot encapsulate all of life which is dynamic.

from Anna Karenina by Leo Tolstoy page 213 fiction ~5 min read

Vronsky’s life was especially fortunate in that he had a code of rules which unquestionably defined everything that ought and ought not to be done. The code embraced a very small circle of conditions, but the rules were unquestionable and, never going outside that circle, Vronsky never hesitated a moment in doing what ought be done. These rules determined unquestionably that a card–sharper must be paid but a tailor need not be, that one should not lie to men but may lie to women, that it is wrong to deceive anyone but one may deceive a husband, that it is wrong to pardon insults but one may give insults, and so on. These rules might not all be very reasonable or very nice, but they were unquestionable, and in fulfilling them Vronsky felt at ease and could hold his head high. Only most recently, in regard to his relations with Anna, had he begun to feel that his code of rules did not fully define all circumstances, and to envisage future difficulties and doubts in which he could no longer find a guiding thread.

His present relations with Anna and her husband were simple and clear. They were clearly and precisely defined in the code of rules by which he was guided.

She was a respectable woman who had given him her love, and he loved her; therefore she was a woman worthy of equal and even greater respect than a lawful wife. He would have let his hand be cut off sooner than allow himself a word or a hint that might insult her or fail to show her that respect which a woman may simply count on.

His relations with society were also clear. Everyone might know or suspect it, but no one should dare to talk. Otherwise he was prepared to silence the talkers and make them respect the non–existent honour of the woman he loved.
His relations with the husband were clearest of all. From the moment of Anna’s love for him, he had considered his own right to her unassailable. The husband was merely a superfluous and interfering person. No doubt his position was pathetic, but what could be done? One thing the husband had the right to do was ask for satisfaction, weapon in hand, and for that Vronsky had been prepared from the first moment.

But recently there had appeared new, inner relations between himself and her that frightened Vronsky with their indefiniteness. Just yesterday she had announced to him that she was pregnant. And he felt that this news and what she expected of him called for something not wholly defined by the code of rules that guided him in his life. He had indeed been caught unawares, and in the first moment, when she had announced her condition to him, his heart had prompted him to demand that she leave her husband. He had said it, but now, thinking it over, he saw clearly that it would be better to do without that; and yet, in saying so to himself, he was afraid – might it not be a bad thing?

‘If I said she must leave her husband, it means to unite with me. Am I ready for that? How can I take her away now, when I have no money? Suppose I could arrange it... But how can I take her away when I’m in the service? If I say it, then I have to be ready for it, that is, to have money and resign from the service.’

And he fell to thinking. The question of resigning or not resigning led him to another secret interest, known only to himself, all but the chief, though hidden, interest of his whole life.

Ambition was the old dream of his childhood and youth, a dream which he did not confess even to himself, but which was so strong that even now this passion struggled with his love. His first steps in the world and in the service had been successful, but two years ago he had made a blunder. Wishing to show his independence and move ahead, he had refused a post offered to him, hoping that his refusal would endow him with greater value; but it turned out that he had been too bold, and he was passed over. Having willy–nilly created a position for himself as an independent man, he bore with it, behaving quite subtly and intelligently, as if he was not angry with anyone, did not consider himself offended by anyone and wished only to be left in peace, because he liked it that way. But in fact, a year ago, when he went to Moscow, he ceased to like it. He sensed that this independent position of a man who could do anything but wanted nothing was beginning to wear thin, that many were beginning to think he could do nothing but be an honest and good fellow. His liaison with Anna, which had made so much noise and attracted general attention, had lent him new brilliance and pacified for a time the worm of ambition that gnawed at him, but a week ago this worm had awakened with renewed force. His childhood comrade, of the same circle, the same wealth, and a comrade in the corps, Serpukhovskoy, who had graduated in the same year, had been his rival in class, in gymnastics, in pranks, and in ambitious dreams, had come back from Central Asia the other day,* having received two promotions there and a decoration rarely given to such young generals.

As soon as he arrived in Petersburg, he began to be talked about as a new rising star of the first magnitude. Of the same age as Vronsky and his classmate, he was a general and expected an appointment that might influence the course of state affairs, while Vronsky, though independent and brilliant and loved by a charming woman, was none the less only a cavalry captain, who was left to be as independent as he liked. ‘Naturally, I do not and cannot envy Serpukhovskoy, but his rise shows me that, if one bides one’s time, the career of a man like me can be made very quickly. Three years ago he was in the same position I am in now. If I resign, I’ll be burning my boats. By remaining in the service, I won’t lose anything. She said herself that she didn’t want to change her situation. And, with her love, I cannot envy Serpukhovskoy.’ Twirling his moustache in a slow movement, he got up from the table and walked around the room. His eyes shone especially brightly, and he felt that firm, calm and joyful state of mind which always came over him after clarifying his situation. As after previous squarings of accounts, everything was clean and clear. He shaved, washed, took a cold bath and went out.

—Leo Tolstoy, Anna Karenina, p. 213