微隙在所必乘；微利在所必得。少阴，少阳。
While carrying out your plans be flexible enough to take advantage of any opportunity that presents itself, however small, and avail yourself of any profit, however slight.
There is a story of a wanderer who passed through a flock of sheep(一群羊 yìqúnyáng) and emerged with one in tow, as if he had entered the flock this way.

When Wu Qi was being pursued by noble archers he clung to the already-dead king's corpse (尸体 shītǐ), which was pierced by several arrows. Even on the brink of death he took an opportunity: a law against mutilating (残害 cánhài) a king's body meant the archers' families were all severely punished.

Opportunities are not always seen as such, for example wher enemy's mistakes are seen as lucky only in the respite gained. Being not only observant (善于观察 shànyúguānchá) but also thoughtful (深思熟虑 shēnsīshúlǜ) is hence important. Flexibility (灵活性 línghuóxìng) is another key skill, being able to quickly adapt and take advantage of opportunities that appear.