Leo.da Vinci may have some relevence to the subject, but as to the significance of Browns book could be misleading , I've yet to be convinced of his theories; we can all conjure up a convicing case on almost any subject if we set our minds to it.

Leo da Vinci was a great thinker, but not the genius that people have claimed , a lot of his ideas were pie in the sky , a fanciful minded persons, a butterfly in thinking hopping from one idea to another,hungry for new ideas, an impatience to discover how nature worked almost to the point of obsession , but rarely did he ever bring his ideas to life .He was a man that was easily bored, rarely prepared to put the mileage in.afterall he was regarded for his time as a tradesman , some have argued ,a cowboy Artisan! a jack of all trades! the Mister Bodger of his time, but a highly intelligent conman,  doing the big sale, but so often he rarely came up with the goods, he was a drifter .For instance he spent most of his life tinkering with the Mona Lisa, why people rate this as an intriguing painting, the so called inigmatic smile, it appears more of a smirk to my eye;a close anatomical study of proportions will show she was  a mishapen woman  ie. the axis of the head to shoulders etc are unbalanced, reminisent of ET , the shoulders and brests appear misplaced ! and as to the fascination he held for this women, well it certainly wasn't for her beauty !

The famous" last supper " a tempra murial is full of faults it was contrived and executed in haste,any art historian will confirm the points of perpective do not work and the tempra was simply painted at speed onto dry plaster, wereas a traditional Fressco was to work a small section of wall onto wet plaster, this method required merging the paint pigment into the wet plaster.thus preserving the image, today barely a fraction of the original work remains intact.

so the debate goes on !!