In respect to the four forms in question, viz., wit, wot, wiss, wisst, the first seems to be the root; the second a strong præterite regularly formed, but used (like οἶδα in Greek) with a present sense; the third a weak præterite, of which the -t has been ejected by a euphonic process, used also with a present sense; the fourth is a second singular from wiss after the manner of wert from were, a second singular from wit after the manner of must, a secondary præterite from wiss, or finally, the form wisse, anterior to the operation of the euphonic process that ejected the -t.
[§ 317]. In the phrase this will do = this will answer the purpose, the word do is wholly different from the word do, meaning to act. In the first case it is equivalent to the Latin valere; in the second to the Latin facere. Of the first the Anglo-Saxon inflection is deáh, dugon, dohte, dohtest, &c. Of the second it is dó, doð, dyde, &c. I doubt whether the præterite did, as equivalent to valebat = was good for, is correct. In the phrase it did for him = it finished him, either meaning may be allowed.
In the present Danish they write duger, but say duer: as duger et noget? = Is it worth anything? pronounced dooer deh note? This accounts for the ejection of the g. The Anglo-Saxon form deáh does the same.
[§ 318]. Mind—mind and do so and so.—In this sentence the word mind is wholly different from the noun mind. The Anglo-Saxon forms are geman, gemanst, gemunon, without the -d; this letter occurring only in the præterite tense (gemunde, gemundon), of which it is the sign. Mind is, then, a præterite form with a present sense; whilst minded (as in he minded his business) is an instance of excess of inflection; in other words, it is a præterite formed from a præterite.
[§ 319]. Yode.—The obsolete præterite of go, now replaced by went, the præterite of wend. Regular, except that the initial g has become y.
Did, from do = facio, is a strong verb. This we infer from the form of its participle done.
If so the final -d is not the same as the -d in moved. What is it? There are good grounds for believing that in the word did we have a single instance of the old reduplicate præterite. If so, it is the latter d which is radical, and the former which is inflectional.