Anna Karenina by Part 3 Chapter 15 Page 8

The recollection of her son suddenly roused Anna from the helpless condition in which she found herself. She recalled the partly sincere, though greatly exaggerated, role of the mother living for her child, which she had taken up of late years, and she felt with joy that in the plight in which she found herself she had a support, quite apart from her relation to her husband or to Vronsky. This support was her son. In whatever position she might be placed, she could not lose her son. Her husband might put her to shame and turn her out, Vronsky might grow cold to her and go on living his own life apart (she thought of him again with bitterness and reproach); she could not leave her son. She had an aim in life. And she must act; act to secure this relation to her son, so that he might not be taken from her.