The stuff we humans can do ! I wish my hands were painted like that, except, well, then I wouldn't be able to use them for anything else. Like, I wouldn't be able to conquer evil doers or save the world or crack super secret spy codes or bake pink chiffon cakes or do ballet or macrame or anything! It would be awful! But, you have to admit, they are pretty cool.
I love this piece of art as it shows the variation of hands that have been sketched. The effect of this in the format of a sketch book is that you can experiment in lots of different ways on one page to show the reader or the observer how many different techniques have been used to achieve the final piece.