But this piece is in duple time, and this fifth part is in 3/1, the _tempus perfectum_ of mensurable music, indicated by a circle.[17] Where could the entrances be effected? This the performer must decide for himself, for Frescobaldi never did anything to assist him in his decision; "_intenda mi chi può, che m'intend' io_" ("let him comprehend me who can, I understand myself"), he tells us. We find the same challenge at the beginning of one of his caprices, the tenth in the first book[18] (pp. 77-86). [Footnote 17: The circle, possessing neither beginning nor end, conveys the impression of the infinite, of perfection. This perfection is attributed to the number _three_; according to Franco of Cologne, the chief number, because of the Trinity, "_vera et summa perfectio_." (_Musica et cantus mensurabilis_, Chap. IV.)] [Footnote 18: _Il primo libro di capricci, canzoni francese e ricercari fatti sopra diversi soggetti et arie in partitura. Di Girolamo Frescobaldi, organista in San Pietro di Roma. Novamente ristampati. Con privilegio. In Venezia, appresso Alessandro Vicenti_, 1642. An earlier edition dates from 1626, and is only the collection in a single volume of the works published in 1615 and 1624.] This same volume contains a Ricercata upon the hexachord (pp. 1-14), remarkably developed, and exhibiting a determination suggestive of scholastic restraint; and a _recercar_ with four subjects (p. 137). In the _Canzoni_, grace and interest of movement particularly are revealed; in some pieces expressive themes of a chromatic character lend a certain sentimental charm, while others, for instance those of which mention has already been made, serve chiefly as examples of ingenuity and cleverness. But the _Toccatas_ of Frescobaldi combine all these characteristics, sometimes contrasted with or dominated by, in addition, a stately dignity, an incomparable breadth. And, moreover, they were conceived expressly for the organ, in their more lofty character, and written upon the staff then in use for that instrument.[19] They display all its resources, within a legitimate compass, although limited by the ability of the executants and by the deficiencies of the Italian organ manufacture of the period; the performers being little accustomed to the use of the pedal, and the Italian manufacture less advanced than that of the Germans. In fact, little could be demanded of the organist beyond long-sustained pedal-notes; and never do these works indicate that organs with several manuals were at that time constructed in Italy. [Footnote 19: The following is a facsimile of this tablature, taken from the beginning of the sixth Toccata in the second book (pp. 16-20), _per l'organo sopra i pedali e senza_: [Music]] While in the Toccatas[20] the themes are developed noticeably in what we may term sections or plans, these are strictly contrasts of movement rather than of intensity of sound.