Imagine The Opponent

A fellow student said something which I felt was very good to share with everyone. When you are practising taiji, you need to imagine there is an opponent there. When you are pushing hands, you need to imagine that there is no opponent there.

I think the basic mentality is correct. However, as with all things in taiji, the "between the yes and no" is very important. So while practising taiji, you should imagine that there is an opponent there, you must not be overly focused on the imaginary opponent. This should allow you to instill spirit/meaning into your movements, without them becoming overly stiff. And when pushing hands, while you should imagine that your opponent is not there, you should not be overly focused on ignoring the presence of your opponent. This should allow you to relax while pushing hands, without becoming limp.