Actually it is so difficult that even nowadays the supercomputer cannot win a professional go player. On contrary, Deep Blue already beat Kasparov, the best chess player in the world, several years ago. The theoretical explanation is that there are so many possible and valid moves in each step that it is very difficult to measure and weight every possible choice according to any algorithm. But human player instead can tell the situation by experience or instincts. Some of them are able to analyse directly from the shape of pieces on the board. Of course this is beyond my understanding and even for the most popular and traditional patterns and formularies I can hardly understand when I was young.
Just recently I happen to watch some go tutorials online, I find I begin to understand the former knowledge I learned and remembered but not understood. I guess one reason is of course the age. But I think it is also a feature of learning: one may not understand at once after learning. Instead he needs practice and even rote. A procedure similar to digest but the duration of digesting depends on the abstract/difficulty level of the learning object and also the intelligence level of the learner.
I am lucky to happen to remind some of go basics after so many years without practice with it and without understanding at the learning stage. Maybe sometimes what we need is just patience and the effect of learning gradually becomes understanding.
