Early English Books Online.
The type used for the letter "s" used in the early days of the printing press looks much like an "f". (though only in the intervocalic or interconsonatal instances) When one reads through this type, the first impression is that these people spoke with a lisp. "..in moft pointf of ufuful knowledge."
Note: Is there a word that means a letter inside a word, that applies for both interconsonatal and intervocalic? What about for the letter at the end of a word?