On tense and mood in conditional clauses from Early to Late Latin

In Early and Classical Latin the future perfect is often met with in the protasis of conditional clauses referring to the future. The function is to indicate anteriority in the future. From Classical Latin onwards there is a tendency to use the future perfect in such clauses even when the anterior function is not always very clear, such as in expressions like ‘if I can’, ‘if I have’ or ‘if I live’. In Late Latin, where this usage is quite common, it often seems to be regarded as indicating not tense but mood. In some cases the indicative of the past tenses indicate irreality in Early and Classical Latin and in Late Latin we may encounter the indicative of the imperfect tense in potential and irreal functions. In Late Latin we sometimes meet periphrases with habere in the apodosis of conditional clauses, a usage which would later develop into the conditional mood of the Romance languages.