The word madrigal is derived from mandra, a flock, and denoted, originally, a shepherd's song (Pastorale). As formerly stated, early composers often selected for their masses Gregorian chants, or secular melodies. In the madrigal, however, the composition rested upon original invention, thus allowing more variety in form and contrapuntal treatment. In the madrigal, the composer's endeavor was to express through adequate music, the meaning of the poem: he followed closely, with appropriate motives, the sentiment of the different verses. Strict and elaborate canons and fugues were therefore out of place in the madrigal, in which, though seemingly simple in its construction, the composer found ample opportunity to display his mastery in contrapuntal writing. Great variety in rhythm, poetical expression, characteristic melodies, new and striking harmonies, were considered the necessary qualities of the madrigal. It was generally written in three, four, five, six and even more parts, though writing in five parts seems to have been most in favor and use. The words of a madrigal generally consisted of twelve or fifteen lines, which had no fixed metre, so that the poem appeared more like a free, than a versified recitation. The closing lines often expressed some witty or happy thought like an epigram. The music was governed more strictly by the meaning of the words than it was in the mass, and the counterpoint was more simple and expressive. In some madrigals the voices were treated with exquisite refinement, in a delicate web of counterpoint. Others were composed in simple harmony, note against note. This latter style possessed a diatonic character, out of which the chromatic element of modern music could gradually be developed. The first hints of this new method we owe to Willaert. Adrian Willaert is considered, if not as the inventor of the madrigal, at least as the composer by whom it was given its first artistic form. It may be regarded as the highest form of chamber-music of those days, written and composed for the refined and appreciative amateurs of the best social circles, principally in Venice and Rome. All composers of repute produced works in this favorite form; among others (beside the two most prominent, Willaert and Cyprian de Rore) Constanzo Porta, Constanzo Festa, Verdelot, Arcadelt, Orlandus Lassus, Orazio Vechi and Luca Marenzio, the last named being the best madrigalist of his time. There were other favorite vocal forms of a more general character, which were composed according to a chosen metre, to which the poem was afterward set. The name given to this species of composition was _modus_ (still to be found in the Portuguese term for folk-song, _modinha_) or _aer_, and from this source was derived the modern name, air or aria, which signifies the manner of singing (as we say a person has a certain air or manner), and does not refer, as many suppose it does, to the medium of song; that is, the sound of vibrating air.