Signore Giovanni Francesco Sagredo, a man of noble extraction and trenchant wit. He invented the portable thermometer, says Wikipedia.
I want to know the truth.
I have not, in fact, read Dialogue Concerning the Two Chief World Systems. In that book Galileo argues his astronomical theories as a dialogue between Salviati, who represents Galileo's views, and Simplicio, who represents the orthodox position of the time.
Sagredo is a third character. He's a neutral observer, who fairly considers the arguments of both sides, and on that basis decides squarely for Salviati. This is who I am.