What is the central idea of sonnet 18

The bell is just a signal that the set time of the end of class is passing. the teacher lets you know when it's okay to leave.

The issue of racism greatly inflience herbecause by then there was racio discrimination in the south this affects her such that she will grow up favouring people of her race and undermining the othersracism will build herin earlier days the people of south were oppressed by the whites since they were considered slaves or subject yo the whites.so as a result of this the whites children grew up bearing in mind that they were more superpower than the black