Conditional Clauses - how do I identify them?

Conditional clauses have two obvious signposts that make identification easy: si and nisi. 

The si clause, or the 'if' clause, is called the protasis, and the outcome of the condition is called the apodosis.

Latin would not be Latin without certain irregularities, but don't worry, there are three major types of conditional clauses that are easy to learn:

1) Open/ General Conditions - The sense of a a general condition is flexible. The events of the conditional clause may or may not happen in any tense. 

General conditions use the indicative in the protasis - the si (if) clause - and either the indicative or the imperative in the apodosis. 

Si vales, bene est - If you are healthy, all is well. (Cicero)

2) Future Less Vivid Conditions - future less vivid conditions imply that an action may or may not happen in the future. You will find the present subjunctive in both the apodosis and the protasis. The subjunctive adds to the uncertainty of the outcome.

Si vir bonus habeat hanc vim, hac vi non utatur - If a good man were to have this power, he would not use it.

3) Contrary to Fact Conditions - 'Contrary to fact' comes from the idea that the outcome in the apodosis has not become a reality, but would have done if the apodosis had occurred. It is the most complex conditional clause; nevertheless, the clause can best explained by the two following rules:

1) Present contrary to fact: if x were to happen, then y would happen.

This clause uses the imperfect subjunctive in both the protasis and apodosis.

Si foret in terris, Democritus rideret - If Democritus were on earth, he would be laughing! (Horace)

2) Past contrary to fact: if x had happened, then y would have happened. 

This clause uses the pluperperfect subjunctive in both protasis and apodosis. 

Si felix Troia fuisset, Hectora quis nosset? - Who would have learnt about Hector had Troy been victorious? (Ovid).