5. Be; equivalent to an inflection in the way of voice. To be beaten=verberari, τύπτεσθαι.
6. Am, art, is, are; ditto. Also equivalent to an inflection in the way of tense. I am moving=move-o.
7. Was, were; ditto, ditto. I was beaten=ἐ-τύφθην. I was moving=move-bam.
Do, can, must, and let, are non-inflectional auxiliaries.
B. Classification of auxiliaries according to their non-auxiliary significations.—The power of the word have in the combination of I have a horse is clear enough. It means possession. The power of the same word in the combination I have been is not so clear; nevertheless it is a power which has grown out of the idea of possession. This shows that
the power of a verb as an auxiliary may be a modification of its original power; i. e., of the power it has in non-auxiliary constructions. Sometimes the difference is very little: the word let, in let us go, has its natural sense of permission unimpaired. Sometimes it is lost altogether. Can and may exist only as auxiliaries.
1. Auxiliary derived from the idea of possession—have.
2. Auxiliaries derived from the idea of existence—be, is, was.
3. Auxiliary derived from the idea of future destination, dependent upon circumstances external to the agent—shall. There are etymological reasons for believing that shall is no present tense, but a perfect.
4. Auxiliary derived from the idea of future destination, dependent upon the volition of the agent—will. Shall is simply predictive; will is predictive and promissive as well.