Galileo Galilei was born in Pisa (then part of the Duchy of Florence), Italy, on 15 February 1564, the first of six children of Vincenzo Galilei, a famous lutenist, composer, and music theorist, and Giulia (née Ammannati), who had married in 1562. Galileo became an accomplished lutenist himself and would have learned early from his father a scepticism for established authority, the value of well-measured or quantified experimentation, an appreciation for a periodic or musical measure of time or rhythm, as well as the results expected from a combination of mathematics and experiment. Three of Galileo's five siblings survived infancy. The youngest,
Galileo Galilei letter to Cardinal Orsini. In 1619, Mario Guiducci, a pupil of Galileo's, published a lecture written largely by Galileo under the title "Discourse on the Comets" ("Discorso Delle Comete"), arguing against the Jesuit interpretation of comets. In 1623, Galileo published "The Assayer—Il Saggiatore", which attacked theories based on Aristotle's authority and promoted experimentation and the mathematical formulation of scientific ideas. The book was highly successful and even found support among the higher echelons of the Christian church. Following the success of "The Assayer", Galileo published the "Dialogue Concerning the Two Chief World Systems" (Dialogo sopra i due massimi sistemi del