"Hendrik Laurenszoon Spiegel (11 March 1549 – 4 January 1612) was one of the most important writers and thinkers from Amsterdam in the second half of the sixteenth century.
Spiegel was born in Amsterdam and is seen as a forerunner to the Golden Age of Vondel, Hooft and Huygens. He is the strongest candidate for the unknown author of the first book on Dutch grammar, the Twe-spraack (Twe-spraack vande Nederduitsche letterkunst), which appeared in 1584. (In the past it was thought to be by his friend, Dirck Volckertszoon Coornhert.)
He was a rederijker and founding member of the rhetorician´s chamber called the Egelantier. On ethics, he wrote "Hertspiegel" (a summary of a more complex work), and a short play, "Numa", on the Roman king Numa Pompilius." - (en.wikipedia.org 31.01.2020)