> this left the typesetter an unwelcome choice between moving the letters further apart (creating an awkward space in the lower half) or keeping them close together (creating a dense area or even touching/overlapping symbols in the upper half).

i just want to clarify that when it came to classic printing, the problem was much more pragmatic than aesthetic. The top of the f actually extended beyond the horizontal bounds of its sort[1]. If you didn't use a ligature, you risked damaging either your /f or your /i, but almost certainly you'd notice it when the line didn't pack flush. The the ligature was partly aesthetic, but it existed historically to make the act of printing work easily.

Now that kerning is better supported, 'historical ligatures' are something of a luxury, which is why they're still an opt-in feature in opentype fonts (you can see this distinction, btw, in the `rlig`, `dlig`, `liga`, `clig` and `hlig` opentype features[2]), except for brick, which is opinionated about these things.

[1]: http://commons.wikimedia.org/wiki/File:Metal_type_kerning.sv... [2]: http://en.wikipedia.org/wiki/List_of_typographic_features