Inkling: Between Want and Don't Want

My teacher was sharing that the key to being able to use your opponent's force is "between want and don't want, between have and don't have (在要与不要之间，在有跟没有之间)". It is very similar to the rest of taiji principles, about how to use force. To be too focused on the intention leads to rigidity. To lack intention, however, leads to a void that can be exploited. So there must be an intention, but it is not strong and can thus be changed when needed. There is something there, but it doesn't take shape; and when it has no shape, it cannot be easily discerned by your opponent and thus he finds it hard to react.