When you say that you agree to a thing in principle you mean that you have not the slightest intention of carrying it out in practice.

Otto von Bismarck (1815-1898) Prussian statesman

(Attributed)

Variants:

• "When a man says he approves of something in principle, it means he hasn't the slightest intention of putting it into practice."
• "When a man says he approves of something in principle, it means he hasn't the slightest intention of carrying it out in practice."