Da Vinci's \textit{Codex Atlanticus}, fols. 395r and 686r--686v, refers to Leonardo Pisano \textit{volgarizzato}, not to Giorgio Valla (Q6082472)

It is shown that folios 395r, 686r--686v of the \textit{Codex Atlanticus}, anonymous folios, inserted in Leonardo da Vinci's notebook, do not deal with the duplication of the cube proper, but rather with the extraction of the cube root by the geometrical methods invented by Archytas of Tarentum and Philo of Byzantium. These ancient methods were translated into Latin by Gerard of Cremona, to be subsequently adapted to arithmetic in Leonardo Pisano's \textit{Practica geometrie} (1220), later translated into \textit{volgare} in Benedetto da Firenze's \textit{Trattato di praticha d'arismetrica} (1463). This corrects a misattribution, going back to \textit{L. Reti} [``The two unpublished manuscripts of Leonardo da Vinci in the Biblioteca Nacional of Madrid. II'', Burlington Mag. 110, No, 779, 81--89 (1968), \url{http://www.jstor.org/stable/875523}] and repeated often since that time, which sees those folios as originating in Giorgio Valla's \textit{De expetendis et fugiendibus rebus} (1501). The author also points out the methodological flaws that led to the misattribution (the basic flaw being ``to isolate two texts beforehand to show, on the basis of vague similarities, that one is the source of the other'').