Newton and the layperson
Newton’s notion of BODY (existing in-and-of itself) is [in a sense] an acknowledgment and a further assertion of layman’s understanding of body: yours, mine, etc. This is not to suggest anything along the lines of brilliance (Laws of Motion) follows science building on the things we understand and definitely not to say science gone fishin when it goes on fishing expeditions.
There’s not much choice: just DO, with DESCRIBE as a part of doing.
I can read a book. So book is an entity that can be read. Did anything happen to the book as a result of reading? Looks happy. So this entity can be characterized in terms of what operations can be performed on it and in terms of the (emotional) terminology employed to describe its properties (looks) in the context of reading (operation).
Do something more definite?
If you give me a piece of string, then I can align the two endpoints and hold them together with my thumb and forefinger letting free fall of the string in between and after some more words like these I have two strings of the same length and this length (description) is determined by equations involving the definite deeds performed.
I am sorry it doesn’t go all the way:
Geometry is a form of algebra.
Conceptual Mathematics, page 378