'Two principles'
Note from The Achievement of France in Part One of Reflections On The Revolution In France

It did not suit Burke here to add to the spirit of gentleman (i. e. honour) and religion, a third great impulse that has guided human affairs, viz. Liberty.

NB. Grieve misses Burke's point that the two principles (honour and morality) are restraints upon behaviour; the spirit of liberty is merely a resentment of restraint. — Philip Atkinson