Chapter 28 At the Bates' home:
...till Jane Fairfax was quite ready to sit down to the pianoforté again. That she was not immediately ready, Emma did suspect to arise from the state of her nerves; she had not yet possessed the instrument long enough to touch it without emotion; she must reason herself into the power of performance; and Emma could not but pity such feelings, whatever their origin, and could not but resolve never to expose them to her neighbour again.
I do not understand Emma's meaning in the highlighted parts of this passage. Can anyone clarify what is meant here please?