The future is a functional litmus test for what is mind rather than merely neural, and for what is affection of the spirit rather than merely animal emotions.
Exactly the part of you that can reason about the future is your mind. The remainder of your neural function is not.
Exactly that in you that bears on the future is your spirit.
These are not definitions, much less explanations, of mind or spirit, but rather only tests for detecting what is or is not mind or spirit.
But conclusions and assumptions do flow from taking the test to be valid. And I espouse every such conclusion or assumption I have been able to think of. For example, that the mind is part of the spirit. Or that, if it were shown that storing nuts for the winter is not instinctive but a matter of planning, then squirrels have minds.