Emily Dickinson Lexicon

SHALL, v.i. [verb auxiliary. pret. should. Sax. scealan, scylan, to be obliged. It coincides in signification nearly with ought, it is a duty, it is necessary; D. zal, zul; G. soll; Sw. skola, pret. skulle; Dan. skal, skulle, skulde. The German and Dutch have lost the palatal letter of the verb; but it appears in the derivative G. schuld, guilt, fault, culpability, debt; D. schuld, Sw. skuld, Dan. skyld, debt, fault, guilt; skylder, to owe; Sax. scyld, debt, offeuse, L. scelus. The literal sense is to hold or be held, hence to owe, and hence the sense of guilt, a being held, bound or liable to justice and punishment. In the Teutonic dialects, schulden, skyld, are used in the Lord's prayer, as “forgive us our debts,” but neither debt nor trespass expresses the exact idea, which includes sin or crime, and liability to punishment. The word seems to be allied in origin to skill, L. calleo, to be able, to know. See Skill. Shall is defective, having no infinitive, imperative or participle. It ought to be written shal, as the original has one l only, and it has one only in shalt and should.]

1. Shall is primarily in the present tense, and in our mother tongue was followed by a verb in the infinitive, like other verbs. “Ic sceal fram the beon gefullod,” I have need to be baptized of thee. Matth. iii. “Ic nu sceal singan sarcwidas,” I must now sing mournful songs. Boethius. We still use shall and should before another verb in the infinitive, without the sign to; but the signification of shall is considerably deflected from its primitive sense. It is now treated as a mere auxiliary to other verbs, serving to form some of the tenses. In the present tense, shall, before a verb in the infinitive, forms the future tense; but its force and effect are different with the different persons or personal pronouns. Thus in the first person, shall simply foretells or declares what will take place; as, I or we shall ride to town on Monday. This declaration simply informs another of a fact that is to take place. The sense of shall here is changed from an expression of need or duty, to that of previous statement or information, grounded on intention or resolution. When uttered with emphasis, “I shall go,” it expresses firm determination, but not a promise.
2. In the second and third persons, shall implies a promise, command or determination. “You shall receive your wages,” “he shall receive his wages,” imply that you or he ought to receive them; but usage gives to these phrases the force of a promise in the person uttering them. When shall is uttered with emphasis in such phrases, it expresses determination in the speaker, and implies an authority to enforce the act. “Do you refuse to go? Does he refuse to go? But you or he shall go.”
3. Shall I go, shall he go, interrogatively, asks for permission or direction. But shall you go, asks for information of another's intention.
4. But after another verb, shall, in the third person simply foretells. He says that he shall leave town to-morrow. So also the second person; you say that you shall ride to-morrow.
5. After if and some verbs which express condition or supposition, shall, in all the persons, simply foretells; as, If I shall say, or we shall say, Thou shalt say, ye or you shall say, He shall say, they shall say.
6. Should, in the first person, implies a conditional event. “I should have written a letter yesterday, had I not been interrupted.” Or it expresses obligation, and that in all the persons. I should, Thou shouldst, He should, You should, have paid the bill on demand; it was my duty, your duty, his duty to pay the bill on demand, but it was not paid.
7. Should, though properly the past tense of shall, is often used to express a contingent future event; as, if it should rain to-morrow; if you should go to London next week; if he should arrive within a month. In like manner after though, grant, admit, allow.