He knew that people do not use vellum to write on anymore.

知道人们已不再羊皮纸写字。

He saw pieces of vellum, animal skin that people wrote on in the past.

看到了多张羊皮纸，这是过去人们来写字的兽皮。

The other aspect is you think well why would he do it on vellum?

另一方面你会想为什画在皮纸上？

But once I'd started looking at Leonardo and vellum, which is basically parchment.

但当我开始看达和皮纸的联时，皮纸一般都是羊皮纸。

We've got no drawings about Leonardo on vellum on animal skin.

我们以前没有发现达皮纸画的画。

I think the point about it being vellum is really interesting.

我觉得关于皮纸这点很有趣。

Now this was executed on vellum I understand, so that's something usually used in codex or a book production.

我知道这幅画是画在皮纸上的，这种材质通常是于古抄本或者书。

And once you're thinking about vellum and coloured chalks on vellum all of this falls into place.

一旦你想到皮纸和在皮纸上染色粉笔画，这些内容都说得通了。

And one of the things he did very brilliantly is to use the natural base colour of the vellum to shine through.

有一点是做得非常聪明的就是利皮纸的自然底色营造了一种光彩。

And a piece of evidence which had been lurking there rather unscrutinised which we didn't really need to think about Leonardo and vellum.

这个证据一直都在，只是我们没发现，我们真的很难想到它跟达和皮纸有关。

The medieval Mappa Mundi in England's Hereford cathedral, for example, is little more than drawings on vellum, or stretched calfskin, and it lacks Ptolemy's geometric method.

比如，中世纪制作的英格兰赫里福德教堂世界地图不过是些绘在羔皮、或者说拉伸了的犊皮上的图案，没有使托勒密的几何方法。

He talks about Jean's box of pigments, he talks about how do you get double and single sheets which is cutting vellum out of a irregular shaped skin.

说到Jean的颜料盒，说到怎样拿到双层的和单层的纸，从不规则的动物皮上割下皮纸。

Your initial reaction, you see a drawing on ink coloured chalks, but also ink washes on vellum, the initial reaction of course is Leonardo didn't do that.

你的第一个反应，当你看到一幅彩色粉笔画的画，还在皮纸上看到水墨，第一个反应当然是这不是达画的。

And I wondered if because there's no other works that we know of which Leonardo worked on vellum, it made a difference in terms of attribution according to technique?

我想知道，因为我们没见过达皮纸画的画，这会不会影响了我们根据画法来鉴定的确定性？