“Failure is the key to success; Each mistake teaches us something.” O-Sensei
This is my favorite quote from O-Sensei for a variety of reasons. One of the main reasons is that it embodies my personal philosophy. This is not just limited to Aikido, but to life in general. In life, as with Aikido, failure is inevitable. Look back on your own life. How long did it take you to learn to walk, to speak, or to learn your profession? Can anyone honestly say that they accomplished these tasks the first time? I thought not. The reality is that failure is unavoidable, and is sure to be your truest companion through life.
Most people are disappointed by failure because they expect perfection. This is faulty reasoning when going to an Aikido class, though. Perfection is a sign of mastery, and if one can truly master a thing (be it Aikido or anything else) there is nothing left to learn. The impressive thing about Aikido is that it does not have a glass ceiling. There is no upper limit. Even O-Sensei trained when he was recognized as the master of his art. Even he, at his highest level of skill, saw fit to improve upon what he had built, presumably because he was not satisfied on some level. We should expect failure, because perfection is impossible.
Since we cannot avoid failure, we should embrace it fully, in Aikido and in life. Personally, I find it to be the best teacher: No organization can compare to the school of hard knocks. For me, the hard things are best remembered, while that which is easily earned is just as easily forgotten. Life is hard, Aikido is hard, so you should expect to fail. It makes life more interesting!