The ct and st combinations are from historical precedent and I always view them as more decorative and less utilitarian. (Many designers overdo them, IMHO, and they are often too distracting to use.)

Fi should never be needed if the designer has spaced or designed the character correctly. In addition if the typeface is spaced so tightly that it needs an Fi ligature that ligature could end up being confused with an h or another glyph that I'm suddenly blanking on. Same goes for ft. If the letters aren't designed to avoid it that ligature could end up looking like and H.

There is much coming out of tradition in the craft and the old limitations of hot metal type or, more recently, 8-bit character sets. Today, with OpenType there are a great many ligature possibilities, some of which are not even apparent to the casual reader. Script type, partiiculary joined cursive, may contain dozens of ligated pairs. The connections typically are there to mimic handwriting.
Many pairs are not seen in all languages in roman faces. The combinations fj ffj fh ffh fb ffb appear in modern large text families with broad Latin language support. Discretionary ligatures like ct and st grew out of calligraphic tradition. They are available in many faces but are rarely used. Sometimes kerning pairs fit the bill for combinations like ti and ft.

ChrisL

There are also many threads on Typophile on this subject. If you use the advanced site search on google with the term ligature you will see them all. Happy Reading!

What is (was) the use/purpose of the "ct", "st" combinations ?

The same as two t's with one cross bar. Or the loop of an f that returns to start a new letter. Efficiency. It isn't apparent from type itself but if you see it written out you can see that the connection is the result of not lifting the pen.

Here are two examples. One is more like type & the other is more like wrtting you might do with a ball point pen today. But they both use a stroke that is not lifted between c&t.

Eben thank you, for the very insightful note.

However, wouldn't joining the "ct" or "st" while
writing require the writer to draw the stroke in
the opposite (unantural) direction of writing
i.e. up and left, rather than down and right.

Also would it also not mean that, he would have
to re-draw or traverse over an already drawn stroke,
thus making that part thicker and/or uglier ?

Obviously you can lift the pen. Or just a use a font. But... if you are writing and joining letters the "unnnatural" shape as you put it has a purpose I think. If you try it you will see that pulling the line in other directions to the right or diagonally makes the c stop "reading" as a c. Maybe you can find a way. If you do you should show us!

A related point: It used to be that the s was a long s much of the time. Like this: ſ. Look in an old book from 17XX. Or in the example above. Under "Perfectus". It says "potest". Or rather "potsſt".

And if you connect it to the t - How would you do that? Exactly.

And the c to t join followed. As did the st when the long s died out.

So in some ways the answer to the question is also just "tradition".

It may seem unnatural to you but then you don't live in the world of the long s. Or use a quill pen.

I am serious about being interested in your alternatives BTW!

Eben, I think you've misunderstood, or rather it was I who was not able to communicate properly.

What I meant was, today when we "write" the "c" and "s" we start from the top, and go to the bottom. By what you have told me, for efficiency in writing fast, and for the connection between ct and st to work, the writer would have to start from the bottom (or lower) part of c and s complete it, do the join and then write the "t" from top to bottom again. It is this way of writing, that I found unnatural as per today's standards.

In the second image that you've provided, I wonder why the writer has not connected the "c" to the "t" from the bottom like the "a" and the "c" are connected, I think what has happened in the process of connecting the "c" to the "t" from the top, a small smudge of ink can be seen on top of "c".

Oh! I see.

If it was one you would be correct. And you are correct in the sense that - it is one stroke the way we write now. So what you are saying makes sense. But when you make the c as shown in these examples it's actually a two stroke process. First the lower left portion and then the top stroke. You can see the ink overlap which is a clue in this image. You say it before when you said a small smudge of ink can be seen on top of “c”

Look also at the o & e too for help seeing it. The o uses the same stroke as the c on the left as does the e.

This image is bigger so it may make more sense. You will have to scroll it because it doesn't fit the template. Sorry.

Still, can you see it now?

But I should point out too - the ct ligature parts are also two. The pen isn't pushed. Only pulled. So maybe it isn't so efficient in this case. But the long s & t is! The top of the long s becomes the the downstroke of the t.

Eben, I remember learning this years ago, but had forgotten about it. The way the ct & st ligature used to be formed makes a lot of sense. If you look at your latest sample the ligature fits right into the text and doesn't call attention to itself, well not very much anyway. Perhaps if more designers thought about how they were originally formed they wouldn't become such awkward decorative frou frou glyphs.

I have a lot more clarity on this issue.

Thank you all.

Richard - your welcome.

Tiff, that's how I feel too. But of course it's easier said than done. ;-)

'Just read this thread. This was one of those things I was never was very clear about. Thanks very much for describing it so well.