Answer: Typography

There is a phenomenon in the field of typography known as a “river” that typesetters go out of their way to avoid. By pure coincidence there will frequently be gaps in the text such that the spacing between words aligns in such a fashion as to create a visible white line made out of slightly-staggered gaps in preceding lines. The gap appears unnatural to the eye and looks almost like a white slash or “river” in the page.

Finding and removing these white rivers via careful adjustment of the typeset is serious business in the industry; typographer Geoffrey Dowding explains, in Finer Points in the Spacing & Arrangement of Type just how seriously the matter is taken:

A carefully composed text page appears as an orderly series of strips of black separated by horizontal channels of white space. Conversely, in a slovenly setting the tendency is for the page to appear as a grey and muddled pattern of isolated spats, this effect being caused by the over-widely separated words. The normal, easy, left-to-right movement of the eye is slowed down simply because of this separation; further, the short letters and serifs are unable to discharge an important function—that of keeping the eye on “the line”. The eye also tends to be confused by a feeling of vertical emphasis, that is, an up & down movement, induced by the relative isolation of the words & consequent insistence of the ascending and descending letters. This movement is further emphasized by those “rivers” of white which are the inseparable & ugly accompaniment of all carelessly set text matter.

Is there anything worse than a river in the world of typesetting? It turns out there is. If you’re so careless with your typesetting that multiple rivers touch, then you create, you guessed it, a lake or hole. We’re not sure exactly where creating lakes or holes of negative space in your typography ranks in terms of typographical sins, but given the disdain Mr. Dowding shows above for a mere river in the text, we’d be inclined to believe leaving typographical lakes or holes in your typesetting is a mortal sin.