Suppose you are playing lacrosse and you have the ball and you are trying to get past defenders who are trying to knock the ball out of your stick. Wouldn't it be nice if you could just grab the ball with your hands? This would be illegal though. Wouldn't it be nice if you could clamp the ball between two sticks? It might keep you from dropping the ball and it would be hard to pass or receive the ball and - it's illegal.
There's a technique, a legal one, that's almost as effective as grabbing the ball with your hands - it's cradling. Cradling is a swinging and almost shaking motion that keeps the ball in the stick. Part of the reason it works is the centrifugal force that pushes the ball into the stick. It also presents a moving target making it harder for your opponent to check your stick
It's important to protect your stick while cradling - to keep your stick close to your body. Like football, you want to keep the ball away from your opponent and close to your body. With practice you'll develop a 'feel' for where the ball is in your stick.
Click below for a video demonstration