So the semicolon is exactly what it looks like: a subtle hybrid of colon and comma. Actually, in ancient Greek, the same symbol was used to indicate a question. And it still seems to have a vestigial interrogative quality to it, a cue to the reader that the writer is not finished yet; she is holding her breath. For example, if the sentence above—“She looked at me; I was lost for words”—occurred as dialogue in a piece that I was copy-editing, I would be tempted to poke in a period and make it into two sentences. In general, people—even people in love—do not speak in flights that demand semicolons. But in this instance I have to admit that without the semicolon something would be lost. With a period, the four words sink at the end: SHE LOOKED at me. The semicolon keeps the words above water: because of that semicolon, something about her look is going to be significant.