Mortimer was one of the most gifted draughtsmen of his generation. Here
he has sketched an imaginary battle between flayed human figures, or 'ecorchés'. The battle is repeated
below in skeletal form.
According to a contemporary, Mortimer was able to draw
a compleat skeleton of the human figure, in the most difficult attitude that could be devised, & begin at the heel; & then, with different coloured ink, he would clothe it in muscles,¿ & begin them at the same part; but what was still more amazing,
he never altered a line.