Of the three later Vedas, the Samaveda is much the most closely connected with the Rigveda. Historically it is of little importance, for it contains hardly any independent matter, all its verses except seventy-five being taken directly from the Rigveda. Its contents are derived chiefly from the eighth and especially the ninth, the Soma book. The Samaveda resembles the Yajurveda in having been compiled exclusively for ritual application; for the verses of which it consists are all meant to be chanted at the ceremonies of the soma sacrifice. Removed from their context in the Rigveda, they are strung together without internal connection, their significance depending solely on their relation to particular rites. In form these stanzas appear in the text of the Samaveda as if they were to be spoken or recited, differing from those of the Rigveda only in the way of marking the accent. The Samaveda is, therefore, only the book of words employed by the special class of Ugatri priests at the soma sacrifice. Its stanzas assume their proper character of musical Samans or chants only in the various song-books called ganas, which indicate the prolongation, the repetition, and the interpolation of syllables necessary in singing, just as is often done in European publications when the words are given below the musical notation. There are four of these songbooks in existence, two belonging to each division of the Veda. The number of Samans here given of course admitted of being indefinitely increased, as each verse could be sung to many melodies.