Quotation out of context (1): Epiphanic Stand-Alones

I've been thinking about quotations out of context for a long time: probably since Ray Bradbury made me fall in love with Yeats without my reading a word of him except Bradbury's quotations in title and epigraph. When such quotations are great -- and really that's the most fundamental reason for wanting to quote, or at least for remembering quotations, getting them by heart -- there are two ways they can be great: