Vary the Mode of Action not always the same way, so as to distract attention, especially if there be a rival. Not always from first impulse; they will soon recognise the uniformity, and by anticipating, frustrate your designs. It is easy to kill a bird on the wing that flies straight: not so one that twists. Nor always act on second thoughts: they can discern the plan the second time. The enemy is on the watch, great skill is required to circumvent him. The gamester never plays the card the opponent expects, still less that which he wants.

THE ART OF WORLDLY WISDOM BY BALTHASAR GRACIAN
TRANSLATED BY JOSEPH JACOBS 1892