Subject Complement

subject complement: the word (with any accompanying phrases) or clause that follows a linking verb and complements, or completes, the subject of the sentence by either (1) renaming it or (2) describing it

"The principle entrance, which had almost the breadth of a church door, was in the angle between the two front gables, and was covered by an open porch, with benches beneath its shelter."
                                                                                          -The House of the Seven Gables
                                                                                                  by Nathaniel Hawthorne

The subject complement describes the "principle entrance" in the excerpt above. It helps the reader to visualize the setting and gain a better understanding of the enormity and grandeur of the House. Hawthorne includes this description to help the reader to see and to communicate the wealth of the original owner. Hawthorne wants the reader to know that the family was well off and is used to being served, as they live in a mansion. This contrasts with the inhabitant's current predicament, poor (mentally, physically, socially, socioeconomically), working class, old, and dying. Hawthorne wants to communicate that the best way to live is to work for yourself and not expect to be waited on and pampered. Hawthorne wants the reader to come away with the impression that all should be equal and treated fairly, not be excused because of their social status.