The Subjunctive

Because speakers of modern English seldom use the subjunctive mood, the Old English subjunctive is difficult for us to get used to. We do still use it when stating conditions contrary to fact, as in:

If I were a carpenter,
and you were a lady,
would you marry me anyway?

Here the subjunctive were (the indicative would be was) suggests that the speaker is not in fact a carpenter.

We also use the subjunctive in noun clauses following verbs of desiring, commanding, suggesting, and so on. For example:

The king commanded that the knight go on a quest.

The king desired that the knight go on a quest.

I suggest that you be a little quieter.

I move that the bypass be routed east of town.

I wish that he were wiser.

Here the subjunctives tell us that the condition described in the noun clause is not a present reality or a future certainty, but a possibility mediated by someone's desire.

Some of these usages are disappearing: the first two examples above sound a little archaic, and it would now be more idiomatic to say "The king commanded the knight to go on a quest" and "The king wanted the knight to go on a quest," using an infinitive construction rather than a subjunctive.

Aside from these common usages, the subjunctive now appears mainly in fixed or formulaic expressions, for example, "come what may," "thanks be to God."

The good news from Old English is that verbs in the subjunctive mood are not marked for person, so you don't have a complete new paradigm to learn. The bad news is that the subjunctive is far more common in Old English than in modern English, and you must get used to seeing it in environments where you do not expect it.