Once we accept the crucial concept that Leonardo Da Vinci was a Pythagorean, some misconceptions or dilemmas could be interpreted fairly easily:
1) Almost all of his writings and drawings in various codices were done with his left hand, writing from right to left and could only be read with the help of a mirror. If those codices were intended to be reviewed by the public, then why did he complicate his life that way? Usually some researchers would jump quickly to the conclusion that he was left-handed or ambidextrous. He is not; In codex Atlanticus Leonardo drew his left hand in training.

This is the very text explaining his drawing:
"Representing the 'weary hand', that is to say, the left hand, of the master practising his left-handed writing."
Leonardo only used his right hand (the Ora hand) for painting, which he regarded as a higher act of creativy. Once his right hand was impaired he could not paint anymore, but still could write and draw. From the same source as above, we quote an anecdote as follows:
"On 10 October Antonio do Beatis, (Itinerario del Cardinale d'Aragona) mentions a visit of the Cardinal of Aragon to Leonardo, 'over seventy years old', and names three paintings: the portrait of 'a certain Florentine lady', St John the Baptist and St Anne (31, 35 and 37), 'all most perfect; but it is true that since he is affected by a kind of paralysis of the right hand, no good work can be expected of him any more. There is a Milanese (Francesco Melzi) who works fairly well and although Leonardo can no longer handle colours with his previous subtlety, he can still draw and teach others."
The explanation is that since Leonardo was a Pythagorean he must follow one of the strict aphorisms of the sect.
"IX. Offer not your right hand easily to anyone. This warns the disciple to keep his own counsel and not offer wisdom and knowledge (his right hand) to such as are incapable of appreciating them. The hand here represents Truth, which raises those who have fallen because of ignorance; but as many of the unregenerate do not desire wisdom they will cut off the hand that is extended in kindness to them. Time alone can effect the redemption of the ignorant masses" (Hall, Manly, LXVIII).