VERBS, AUXILIARY. Should = "ought;" "was to"Should is sometimes used as though it were the past tense of a verb "shall," meaning "is to," not quite "ought." Compare the German "sollen."
“The Senate heard them and received them curteously, and the
“About his son that should (was to) have married a shepherd's
people the next day should (were to) assemble in counsell to give
them audience.” N. P. Alcibiades, 170. In the following, should is half-way between the meaning of "ought" and "was to." The present, shall, or "am to," might be expected; but there is perhaps an implied past tense, "I (you said) was to knock you."
“Petruchio. And rap me well, or I'll knock your knave's pate.
Grumio. My master is grown quarrelsome: I should knock you,
And then I know after who comes by the worse.