Shoshin in English translates as the “beginner’s mind”, this concept is drawn from Zen philosophy and taken into Budo which is a Japanese term meaning "martial way" and refers to Aikido and other Martial Art disciplines whose ultimate goal is spiritual, ethical and self-improvement through training in there Martial Art.
Using Shoshin in your everyday practice of Aikido means having an open, empty mind, uncluttered by preconceived notions which give you a kind of attitude that you probably had when you first started Martial Arts. You were excited and eager to learn therefore embracing Shoshin as you listened and observed more and didn't try to add value by constantly contributing gems of wisdom from your own experience whatever that be or no experience but a pre judgment in your mind, but processing the information given to you if it be visual, verbal or both.
You therefore had an attitude of openness, eagerness and had no preconceptions of how to do your techniques, you just wanted to learn and copy and do your best.
This is the mind that you should have in every practice session you participate in, even when you get to the point of learning advanced levels or have practiced Aikido or any other Martial Arts for some length of time. If you maintain a beginner’s mind, even as a higher level practitioner of your Martial Art you’re more likely to not close your mind to further learning.
As the Zen monk Shunryu Suzuki put it in his book Zen Mind, Beginner’s Mind:
Some people think that black belts know it all and those people probably don’t understand or forget that the first black belt is called “Shodan” in Japanese; it literally means “beginning step” so when you receive a black belt it is not the end, it’s the beginning of your learning stage.
If you maintain Shoshin when you are training with others no matter what grade or style you will continue to learn from everyone you meet in some way or form. I have been training over 20 years in Aikido and I found this myself many times training with beginners/new people who teach you to adjust as they may be stiff, non compliant or simply terrified of what's going to happen next. These actions teach you to be aware differently, possibly move differently and expect the unexpected and there curious questions also teach you to think concisely about your movements/actions and angles and the reason why we do things, as ever, action has a reason behind it, which makes everyone involved better people.
I have seen many times when beginners do things unexpected in reactions and simply told to not do that and do this, but as we are practising a Martial Art this is not Budo and Shoshin has been lost as that persons partner is now told to change their reactions in order for them to complete a technique and not find out why it went wrong. If Shoshin is maintained we will remember the beginner’s mind is based on the human principle of humility, and humility exemplifies the true spirit of Aikido. The beginner’s mind is not naive or lacking conviction, it's accepting one’s weaknesses and consciously aware of knowing you don't know or not understanding what has just happened. So improvement in training can only happen when we learn to live with our own individual realities and circumstances to become wiser and grow with it.
The founder of Aikido, Morihei Ueshiba, said “Failure is the key to success; each mistake teaches us something.” The founder also said, “There are times when you may be overwhelmed by the teachings of the Way. At such moments, it is important to continue with the original spirit of a beginner.”
I see all this as a return back to basics and by keeping Shoshin in your mindset, no matter what level or grade you are in Martial Arts your perceptions or ego will always be humble and honest allowing you to progress.