It has been observed here this morning that we are called fanatics. Bless me! That is nothing. Who has not been called a fanatic who has discovered anything new in philosophy or science? We have all read of Galileo the astronomer who, contrary to the system of astronomy that had been received for ages before his day, taught that the sun, and not the earth, was the centre of our planetary system? For this the learned astronomer was called "fanatic," and subjected to persecution and imprisonment of the most rigorous character. So it has been with others who have discovered and explained new truths in science and philosophy which have been in opposition to long-established theories; and the opposition they have encountered has endured until the truth of their discoveries has been demonstrated by time. The term "fanatic" is not applied to professors of religion only...I will tell you who the real fanatics are: they are they who adopt false principles and ideas as facts, and
... Who can tell us of the inhabitants of this little planet that shines of an evening, called the moon? When we view its face we may see what is termed '"the man in the moon,'" and what some philosophers declare are the shadows of mountains. But these sayings are very vague, and amount to nothing; and when you inquire about the inhabitants of that sphere you find that the most learned are as ignorant in regard to them as the most ignorant of their fellows. So it is with regard to the inhabitants of the sun. Do you think it is inhabited? I rather think it is. Do you think there is any life there? No question of it; it was not made in vain. It was made to give light to those who dwell upon it, and to other planets; and so will this earth when it is celestialized. Every planet in its first rude, organic state receives not the glory of God upon it, but is opaque; but when celestialized, every planet that God brings into existence is a body of light, but not till then. ...
[Journal of Discourses. Liverpool, England, 1853-86. 13:267-274, quoted in The Complete Discourses of Brigham Young, Ed. Richard S. Van Wagoner, Smith-Pettit Foundation, Salt Lake City (2009), http://bit.ly/BY-discourses]