In addition to the ordinary forms of correspondence between protasis and apodosis ( cross2297), Greek shows many other combinations expressing distinct shades of feeling. Most of these combinations, though less frequent than the ordinary forms, are no less “regular.” Shift of mental attitude is a known fact of all speech, though the relation of cause to effect must not be obscured. A speaker or writer, having begun his sentence with a protasis of one type, may alter the course of his thought: with the result that he may conclude with an apodosis of another form, in some cases even with an apodosis “unsymmetrical” with the protasis and logically dependent upon a protasis that is only suggested by the form actually adopted. Since either protasis or apodosis may choose the form of expression best suited to the meaning, the student should beware of thinking that conditional sentences invariably follow a conventional pattern, departure from which is to be counted as violation of rule. Some combinations are less usual than others: most of the more common variations from the ordinary type have been mentioned under the appropriate sections, and are here summarized ( cross2356- cross2358). Special cases are considered in 2359-2365.
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].