“He who would learn astronomy, and other recondite arts, let him go elsewhere.”

The quote is part of the commentary on Genesis 1:6-8.

God said, “Let there be an expanse in the midst of the waters and let it separate water from water.” So God made the expanse and separated the water under the expanse from the water above it. It was so. God called the expanse “sky.”

Calvin lived in a time when the new science of astronomy was coming up with discoveries about the nature of the sky and what is in it. This suggestion, that there is water above the sky, is obviously wrong in the light of these discoveries:

Moses describes the special use of this expanse, “to divide the waters from the waters” from which word arises a great difficulty. For it appears opposed to common sense, and quite incredible, that there should be waters above the heaven. Hence some resort to allegory, and philosophize concerning angels; but quite beside the purpose. For, to my mind, this is a certain principle, that nothing is here treated of but the visible form of the world. He who would learn astronomy, and other recondite arts, let him go elsewhere. [...] The assertion of some, that they embrace by faith what they have read concerning the waters above the heavens, notwithstanding their ignorance respecting them, is not in accordance with the design of Moses.

In other words, “Moses”, who was believed at the time to be the author of Genesis, wasn’t talking about how the universe really is, but rather how it appeared to a person at the time. To read it as a book about science is to miss what the author is trying to say.
Similarly, in the story about God creating the “greater light” (Sun) and “lesser light” (Moon) and the stars:

It is well again to repeat what I have said
before, that it is not here philosophically discussed, how great the sun is in the heaven, and how great, or how little, is the moon; but how much light comes to us from them. For Moses here addresses himself to our senses, that the knowledge of the gifts of God which we enjoy may not glide away. Therefore, in order to apprehend the meaning of Moses, it is to no purpose to soar above the heavens; let us only open our eyes to behold this light which God enkindles for us in the earth. By this method (as I have before observed) the dishonesty of those men is sufficiently rebuked, who censure Moses for not speaking with greater exactness.

Remember this was written three hundred years before Darwin. Since the earliest days of the Renaissance, science has discovered things which appear to contradict a literal reading of the Genesis story. Astronomy was the first, and Christian theologians didn’t have a problem with it. The response has always been the same: If you want science ask a scientist. If you want some lessons on how to live a Christian life, read the Bible and ask a theologian.
I picked Calvin specifically for a reason: Most “creation science”/”intelligent design”/whatever it’s called now place themselves in the Calvinist tradition. They would do well to see how he reacted to these “challenges”.

all of darwin’s books:
http://www.gutenberg.org/browse/authors/d#a485

Seriously though, we need an update on darwin’s view before we tell religious people to “go read”

Darwin’s work is 150 years old, sure he got the ball rolling but the field has moved on since then. Science is not writen in stone, if it is it soon becomes dogma. He was a scientist and shouldn’t be hallowed more than any other scientist who has continued working in this field.

Sure it’s great from a knowledge and literal point of view, but that’s preaching to the choir. Darwin’s massive work isn’t going to make a creationist see reason if they’re not willing to read The Complete Idiots Guide to Evolution.

http://etext.library.adelaide.edu.au/d/darwin/charles/