With Sonnet 120 William Shakespeare draws a line under the explanations and excuses offered throughout the previous three sonnets for his own infidelities in relation to his young man, and simply reminds himself now of how awful he felt when his lover treated him in a similar way on those occasions when it was him who was sleeping around with other people. The conclusion Shakespeare comes to is that they both in turn have been through hell, and that their respective debt to each other for each other's transgressions now must surely cancel itself out.