[53] This verb is, unquestionably, a derivative from the Saxon ꞅceal, I owe or I ought, and was originally of the same import. I shall denoted “it is my duty,” and was precisely synonymous with debeo in Latin. Chaucer says, “The faith I shall to God;” that is, “the faith I owe to God.” “Thou shalt not kill,” or “thou oughtest not to kill.” In this sense shall is a present tense, and denoted present duty or obligation. But, as all duties and all commands, though present in respect to their obligation and authority, must be future in regard to their execution; so by a natural transition, observable in most languages, this word, significant of present duty, came to be a note of future time. I have considered it, however, as a present tense; 1st, because it originally denoted present time; 2dly, because it still retains the form of a present, preserving thus the same analogy to should that can does to could, may to might, will to would; and 3dly, because it is no singular thing to have a verb in the present tense, expressive of future time, commencing from the present moment; for such precisely is the Greek verb μέλλω, futurus sum. Nay, the verb will denotes present inclination, yet in some of its persons, like shall, expresses futurition. I have considered, therefore, the verb shall as a present tense, of which should is the preterperfect.
Johnson’s explanation of the meaning of this verb is so perspicuous, that, as foreigners are apt to mistake its use, I shall here transcribe his words. I shall love: “it will be so that I must love,” “I am resolved to love.” Shall I love? “will it be permitted me to love?” “will it be that I must love?” Thou shalt love: “I command thee to love;” “it is permitted thee to love;” “it will be, that thou must love.” Shalt thou love? “will it be, that thou must love?” “will it be permitted thee to love?” He shall love: “it will be, that he must love;” “it is commanded that he love.” Shall he love? “is it permitted him to love?” The plural persons follow the signification of the singular.
I transcribe also the same author’s explanation of the verb I will. I will come: “I am willing to come,” “I am determined to come.” Thou wilt come: “it must be, that thou must come,” importing necessity; or “it shall be, that thou shalt come,” importing choice. Wilt thou come? “hast thou determined to come?” importing choice. He will come: “he is resolved to come;” or “it must be, that he must come,” importing choice or necessity.
Brightland’s short rule may be of some service in assisting foreigners to distinguish the use of these two verbs. It is this:
“In the first person simply shall foretels:
In will a threat, or else a promise, dwells;
Shall in the second and the third does threat;
Will simply then foretels the future feat.”
In addition to these directions for the use of shall and will, it is to be observed, that, when the second and third persons are represented as the subjects of their own expressions, or their own thoughts, shall foretels, as in the first person, thus, “he says he shall be a loser by this bargain:” “do you suppose you shall go?” “He hoped he should recover,” and “he hoped he would recover,” are expressions of different import. In the former, the two pronouns necessarily refer to the same person; in the latter, they do not.
[54] This verb is derived from the Saxon verb willan, velle, the preterite of which is Ic wold.