But the conjunction is often omitted in copulative and adversative clauses, as in Sec.
Then let him deliberately use the adversative but, and proceed to the discussion of B.
They accordingly emphasize the adversative idea, and are properly Subordinate adversative Clauses.
Without the adversative, the colon is to be preferred: "Prosperity showeth vice: adversity, virtue."
Another example is, "Only the star dazzles; the planet has a faint, moon-like ray" (adversative).