There is nothing so practical as a good theory.
Economists are people who wonder if what works in reality can also work in theory.
The best theory is inspired by practice.
Those who are enamoured of practice without science are like a pilot who goes into a ship without rudder or compass and never has any certainty of where he is going. Practice should always be based upon a sound knowledge of theory.
Psychology saves us from mistakes. It makes us more clear as to what we are about. We gain confidence in respect to any method which we are using as soon as we believe that it has theory as well as practice at its back.
There is a distinction, but no opposition, between theory and practice. Each to a certain extent supposes the other. Theory is dependent on practice; practice must have preceded theory.
A theory that you can't explain to a bartender is probably no damn good.
The legislator should keep two things constantly before his eyes: 1. The pure theory developed to its minutest details; 2. The particular condition of actual things which he designs to reform.
It is not paradox to say that in our most theoretical moods we may be nearest to our most practical applications.
Theoretical approaches have their place and are, I suppose, essential but a theory must be tempered with reality.
Thus not only the mental and the material, but the theoretical and the practical in the mathematical world, are brought into more intimate and effective connection with each other.
Critical reflection on practice is a requirement of the relationship between theory and practice. Otherwise theory becomes simply "blah, blah, blah, " and practice, pure activism.
