How does Hamlet expect his mother to change her relationship with Claudius?act 3 sc 4
Gertrude has just accused Hamlet of being mad (because he is the only one who can see the ghost). Hamlet wheels on her and tells her that he is not mad. He implores her to,
"Confess yourself to heaven, Repent what's past, avoid what is to come, and do not spread the compost on the weeds to make them ranker."
He is telling her that she needs to admit her own sin at marrying her husband's brother, whose intentions are unclean, before her husband's body was even cold in the grave. He is telling her not to make it worse by continuing on with Claudius (don't put fertilizer on the weeds or you'll make the weeds grow). He wants her to see Claudius for the evil he truly is. He want his mother to repent. He tells her that she should not continue on with Claudius in the role of wife if she expects to be forgiven. He says,
"But go not to my uncle's bed. Assume a virtue if you have it not."
He is telling her that if she begins to refuse Claudius now it will become easier with each day and she will begin to see him for the evil thing he is.