The quotation argues that serious setbacks can arise as much from one’s own errors as from the actions of an opponent. An adversary’s plans may be difficult to control, but decisions about objectives, resources and acceptable risks remain partly within one’s own control. Poor judgement can therefore create vulnerabilities that an enemy would otherwise struggle to produce.

In a military context, the idea favours discipline, realistic planning and restraint. Expanding objectives unnecessarily or taking avoidable risks can weaken an otherwise strong position. Attention should therefore be directed not only towards anticipating what an opponent might do, but also towards preventing mistakes within one’s own strategy.

The principle also applies more broadly to decision-making. When assessing risk, it can be useful to distinguish external threats from preventable internal failures and to consider whether ambitious plans introduce dangers that careful preparation could avoid.