I’m translating a text from Sanskrit, which has a singular/plural (and, actually, dual) distinction in the second person. It has long been the custom in English translation to render the 2nd singular with ‘thou’, etc. and the 2nd plural with ‘ye/you’, etc., as in Early Modern English (EModE). This creates a suitably archaic and liturgical feel to the translation.
But I’ve come unstuck with the phrase ‘may you be covered’. If I want to replace ‘you’ with ‘thou’, should ‘may’ become ‘mayest’ or not?
My feeling is that ‘may’ is functioning as an auxiliary here. In Modern English, we say ‘he likes it’, but ‘may he like it’. We do not say ‘mays he like it’, the ‘may’ is not a finite verb. So I would expect the same to apply to EModE.
However, we would also apply the same logic to ‘should’. We would say ‘Has he eaten of the tree, whereof I commanded him that he should not eat?’, not ‘… that he shoulds not eat?’. And so I would have expected, applying that logic, to find ‘… that thou should not eat?’. And yet we have in Genesis:
And he said, Who told thee that thou wast naked? Hast thou eaten of the tree, whereof I commanded thee that thou shouldest not eat?
Which leads me to question whether the may would be finite and agree with thou, or not. Should it be ‘mayest thou be covered’ or ‘may thou be covered’, and why? This, to be clear, is in the sense of an imperative: ‘Be covered!’ – only softer.
Generally, you would use mayest with thou. Modal verbs (mayest, might, wilt, wouldst, canst, couldst, shalt, shouldst) were conjugated only in 2nd person singular.
The question is whether you still use mayest if the sentence is in the subjunctive mood, or whether you use the bare infinitive may. With main verbs, the subjunctive mood used the bare infinitive, even in 2nd person singular. Did modal verbs obey the same rules?
The evidence from Shakespeare (one of the two standard exemplars of Early Modern English) is that they did not. Even in constructions we would expect to be in the subjunctive mood, modal verbs are still conjugated by adding an -est. Shakespeare used mayst thou 16 times, and never once used may thou. And the following are clearly wishes:
O Imogen, safe mayst thou wander, safe return again!
In dreadful war mayst thou be overcome,
Or live in peace abandon’d and despised!
long mayst thou live
To bear his image and renew his glories!
Hermia, sleep thou there:
And never mayst thou come Lysander near!
Of all say’d yet, mayst thou prove prosperous!
Of all say’d yet, I wish thee happiness!
Ill mayst thou thrive, if thou grant any grace!
Long mayst thou live to wail thy children’s loss;
Long mayst thou live in Richard’s seat to sit,
And soon lie Richard in an earthly pit!
The last of these examples pairs “mayst thou live” with the subjunctive “soon lie Richard” (not “lies”), so we see that “mayst” was used here in parallel with the subjunctive mood for a non-modal verb.
Your quote from Genesis uses thou shouldest in a context that should be in the subjunctive and Tim Romano has found mayest thou for a wish, that would normally be in the subjunctive mood. My conclusion is that in Middle English, for auxiliary verbs, the conjugation was still “thou mayest”, “thou shouldest” and so forth, even in the subjunctive. As more support for this conclusion, Shakespeare wrote
How dearly would it touch me to the quick,
Shouldst thou but hear I were licentious
And that this body, consecrate to thee,
By ruffian lust should be contaminate!
and clauses starting should always have a counterfactual meaning, something which normally triggers the subjunctive mood.
So use mayest thou.
One more thing—today hardly anybody understands the details of Middle English grammar, so hardly any of your readers will even notice if you use the wrong verb form.