A term used for a brief phrase or motif that recurs at various points in a work. It may be applied to masses of the 15th and 16th centuries unified by the appearance of the same brief phrase at the beginning of each movement, as in parody masses such as Morales's Missa ‘Mille regretz’ (see Head-motif). In the 17th and 18th centuries, it is commonly applied to a figure at the beginning of an aria (see Devisenarie) where the ‘motto’ is stated by the voice and followed by the opening ritornello, as in ‘Lo farò, dirò spietato’ in Act 1 of Handel's Rodelinda (1725). In music of the 19th century, it may apply to a phrase that dominates a composition or recurs within it, generally appearing at the opening and at decisive moments in the course of the movement or the work: examples are Beethoven's ‘Lebewohl’ Piano Sonata op.81a, Berlioz's Symphonie fantastique (where the idée fixe may be called a motto) and Tchaikovsky's Symphonies nos.4 and 5.