No need to look so astonished! It is a fact. These angels congregate in one of my favourite panels in the National Gallery in London. It is a painting by Piero della Francesca entitled the Baptism of Christ. When I was working on a pan-European project some years ago, a sister project, also funded by the EEC (as it then was), worked away in the National Gallery, digitally imaging all the paintings there. Some lunch times I would pop along to see how work was progressing. As you can imagine the rig for imaging these vast masterpieces was huge and the imaging took a considerable time - but what could be seen, which could not have been perceived by the naked human eye was truly gaspworthy. We are all familiar with pricking and pouncing pattern heets to transfer designs from books of patterns or drawings onto fabric for stitching. What I had not grasped until late in life, was that this method was used also by the Grand Masters of painting and their schools. Look closely at the draped garments on the angel to the very left of the detail above.
And now see what is normally invisible to your eye.... pounced dots! The design for this garment was transferred from a cartoon on another source using the prick and pounce technique we know so well. In painting the technique took off in the mid-fifteenth century, depending, as it did, on the more ready availability of paper.