Attacco

Attacco, in music, indicates a short phrase, treated as a point of imitation; and employed, either as the subject of a fugue, as a subordinate element introduced for the purpose of increasing the interest of its development, as a leading feature in a motet, madrigal, full anthem, or other choral composition, or as a means of relieving the monotony of an otherwise too homogeneous part-song. The name comes from the Italian "attaccare", "to unite" or "to bind together."
A striking instance of an attacco used as the subject of a fugue is J. S. Bach's "The Well-Tempered Clavier", No. 27.
When used merely as an accessory, it almost always represents a fragment of the true subject; as in this passage from "Ye House of Gilead," from Handel's "Jephtha".
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In the madrigal and motet, a new attacco is usually introduced with each new paragraph of the verbal text; in the glee, properly so called, the part played by the attacco is less important; while in part-songs, its appearance as a prominent feature is still less frequent. It can, however, be found in John Wall Callcott's "Go, plaintive Breeze," in Felix Mendelssohn's four-part Lied "Türkisches Schenkenlied: Setze mir nicht, du Grobian".