[1] During this period, as a result of a fall from a horse and an inept operation, his health, already delicate, became even more fragile.

He returned to Rome in 1610, and pursued a range of interests including theology, jurisprudence, mathematics and astronomy, as was consistent with prevailing ideas about a cultural education, founded on Aristotelian philosophy.

He was on friendly terms with Cardinal Robert Bellarmine and Maffeo Barberini (later Pope Urban VIII) as well as with Prince Federico Cesi, patron of the Accademia dei Lincei.

[2] In the Accademia dei Lincei he served as a link between scientists who were working in different cities of Italy, and encouraged Galileo, who was facing criticism from conservative circles.

In 1619, the Jesuit Orazio Grassi, writing under the pseudonym Lotario Sassi, published Libra Astronomica ac Philosophica, which attacked Galileo.