A principle is the expression of perfection, and as imperfect beings like us cannot practise perfection, we devise every moment limits of its compromise in practice.
Every living being is an engine geared to the wheelwork of the universe. Though seemingly affected only by its immediate surrounding, the sphere of external influence extends to infinite distance.
To ride a bicycle properly is very like a love affair-chiefly it is a matter of faith. Believe you do it, and the thing is done; doubt, and, for the life of you, you cannot.