If you assent to using your heart to see, you are listening to it and responding to it. The contours of its communication become more clear, and it is strengthened. The mind is brought into deeper relationship with it.
Here we are just talking about a colloquial way of describing "feeling," whether that feeling is for places, people, or whatever else. This is not to say that the heart runs away and suddenly becomes the master. No, it takes great external pressure for that to happen. Here one can order one's activities taking into account how one feels in a given state of affairs.
Where much of the external pressure is currently flowing is towards the executive functions, which our world of symbols and stimuli is constantly feeding and strengthening. So the mind's relationship with itself is strengthened. A powerful tool certainly, but a tool that must still exist in relation with the heart and the rest of the body.
And applying various mental concepts to attempt to drive the heart only goes so far. It all has to be taken together, and balanced together.
