Antecedent
The first half of a period.
What it means
The antecedent (German Vordersatz) is the first half of a period. It sets out a musical idea but does not conclude it, ending instead openly and demanding a continuation. This continuation is formed by the consequent, which carries the idea to its end.
Musical use
In the classical period, the antecedent mostly comprises four bars and ends with a half cadence on the dominant — the sonority stays open, the tonic is not yet reached. Occasionally it also ends with an imperfect full close, in which the tonic does appear but without full closing strength, for instance with the third in the top voice. Decisive in both cases is that the close is weaker than that of the consequent.
Within the antecedent, two smaller units can mostly be distinguished: a pithy basic idea and its continuation to the half cadence. The consequent often begins with the same basic idea, whereby the relationship between the two halves becomes audible, and then continues it differently, so that it ends with a full close.
The model is widespread in themes of the Viennese Classical era, in dance movements, and in songs, and allows numerous variants: the antecedent can be lengthened, lead into a different key, or be interlocked with the consequent.
The antecedent is to be distinguished from the Hauptsatz, which designates the first thematic section of a sonata movement and can itself be built as a period.
Other names
Antezedenz is the designation taken over from Latin, or from English (antecedent); its counterpart is the consequence (consequent), the Nachsatz. The designation is found above all in English-language formal theory; in substance the same thing is meant: the opening, mostly half-cadence-ending first part of a period.
Performance practice
Shape the antecedent as open: its close should ask, not answer. Maintain the tension through the half cadence and do not pull back the closing sound as though everything were over. And approach the consequent as an answer, with awareness of what the antecedent has left open.