Genesis is a very beautiful book describing, as its name suggests, the beginnings of all theologically relevant things. The very first chapter alone has a lot to teach us. Things that you would never come up with if you're not looking for them.
As an example, in the header image, I have included the full description of the second day. Notice anything? This is the one day that lacks a recurring key phrase: "And it was good". This tells us that actually, God does not think the sky is good. It is a thing which separates man from his true potential. As the joke goes, "the sky is the limit, so give up on your dream of becoming an astronaut".
Isn't this an inspiring thing? God wants us to break our limits, and of course eventually, in 1969, we did. Here's the problem: Almost everything I just said is complete and utter rubbish. I made all that up. While it's true that the second day is the only day that God doesn't declare His creative acts good, the conclusion I drew from that was way beyond what the text indicates. I was very deliberately practising eisegesis, and I would hope at least some of my readers would have been ready and prepared to rebuke me for it had I been serious.
So what is eisegesis? Eisegesis is the antithesis of exegesis. Where exegesis is the attempt to shape our views around the natural meaning of the text, eisegesis is imposing external ideas on the text. My example shows just how easy eisegesis is to do. I took a really simple verse in scripture, and I twisted it into... well, I don't even know what that is other than to say it's a weird thought experiment that one ought never perform except to train the mind to spot and combat real world eisegesis.
The point of this article is not to teach my readers that God wants us to surpass our limits, but rather to teach us to stay within them. When God gave us scriptures, He did so as a means of communicating sound doctrine to us. If He wanted us to make up our own doctrines, the Bible would be an ink blot test. For Christ's sake (quite literally), let the scriptures speak, and when they do, listen. Don't treat God like some glorified sock puppet, saying what you want Him to say. Otherwise, a time will come when He will say something you really don't want Him to: "Liar!"