Context for the prism metaphor: optics (Newtonian optics specifically) was one of Algarotti's main interests, and one of his main accomplishments was reproducing the experiments that backed Newton's findings and publicizing his results. He was the first person in Italy to be able to reproduce Newton's results. Other people had failed and concluded Newton was wrong. Algarotti got his hands on some really high-quality prisms and reproduced the results.