The thing about judo is ...
There are a lot of fine lessons that come when you study the martial arts, but one theme that seems to repeat itself over and over is about give and take. If you want to learn something, you have to be open to correction. If you want to have a good friend, you have to be a good friend. If you want to get something, you have to be willing to give something. Life is constantly proving and re-proving Newton's third law of motion: for every action, there is an opposite and equal reaction. What you put into it will equal what you get out of it. And vice versa.
This is beautifully illustrated in judo class. Sometimes you are the tori (person demonstrating a technique). And sometimes you are the uke (person on whom a technique is demonstrated).
Your experience and growth as a judoka will directly relate to how you perform these roles. If you want to master a technique as the tori, you need an uke who will work with you, someone who will take their falls and gradually increase their resistance as you perfect your technique. In return, a good tori will protect his/her uke, making sure that their fall is not too intense so that the performance is repeatable. And then you get the opportunity to switch roles and give and take with your partner as they just gave to/took from you.
It's a fine life lesson as well as a way to succeed in the dojo. When you give of yourself, no matter how scary the fall my look, you open yourself to a plentiful return.