Robert Recorde was a mathematician living in the early 1500s ... born in Tenby ... who introduced some of the common symbols that we use in our arithmetic
https://en.wikipedia.org/wiki/Robert_Recorde
He had a strong mind, training as a physician but choosing to lecture in mathematics at Oxford University
THE CASTLE OF KNOWLEDGE is a poster or broadsheet printed in his lifetime setting out the rationalist viewpoint of the conflict between reason and superstitious fatalism.
https://wellcomecollection.org/works/x8xqpuuc/images?id=z34wr83f
His views must have been respected because they were memorialized in plasterwork at Little Moreton hall in Cheshire. The figure is clearly copied from the print.
The transcription error ... SPEARE instead of SPHERE ... must have confused many people with weaker minds than Robert Recorde's.
