Back to defining spirit (mind, for that matter) and showing it exists as something distinct from body.....
That's too easy. Those who hold the idea of it's all the same and their just interchangeable words and it's yet to be proved etc. don't want to know.
So it's no wonder to me that so many 'think' they can understand Ueshiba for example and yet still say the above.
Not just in Aikido but in life too, it's always a source of amusement to me. You got araes of life which are the domain of spirit or spiritual well being called Religion yet generally full of experts who don't even want to know the difference. You got areas to do with mind yet full of people and experts who can't even define one or have ever seen one. A crazy old world