But, precisely as the central pier is only an intermediate point of support, and not terra firma, so the ending of the Antecedent phrase is never anything more weighty than a semicadence, while the definite, conclusive, perfect cadence appears at the end of the Consequent phrase,--or of the entire period-form.
The reason for this distinction of cadence is obvious.

A period is not two separate phrases, but two related and coherent phrases which mutually balance each other.

The Consequent phrase is not merely an "addition" to the first, but is its complement and "fulfilment." The two phrases represent the musical analogy of what, in rhetoric, would be called thesis and antithesis, or, simply, question and answer.

In a well-constructed period the Antecedent phrase is, therefore, always more or less _interrogative_, and the Consequent phrase _responsive_, in character.
For illustration (Mendelssohn, No.

28):-- [Illustration: Example 44.