It seems paradoxical, but, if you are always right and never make a mistake, you will never truly know everything because you will not know what is wrong. Knowing what doesn't work is just as important as knowing what does. For illustration purposes, language learning gives a clear example of what it means to really learn. I would have to try it, and risk making a mistake in order to know the possible manipulations of work order. The first reason is in order to have confidence in what you do truly know.
Confidence leads to relaxation and a clear mind, which leads to successful encounters.
The second reason is less obvious, but no less important. Basically, if you know this little fact about word order in French, you know something about many other sentences in French as well. This one piece of knowledge is actually a window into a much larger chunk of knowledge. The lesson here is that in order to gain truly useful knowledge of the world so that you can be confident in the end, you have to be willing to risk mistakes. This discovery process is the interesting part of knowledge.