The observer, when he seems to himself to be observing a stone, is really, if physics is to be believed, observing the effects of the stone upon himself. ↗
I should point out, however, that at first some difficulty was experienced in observing the phenomena predicted by the theory, owing to the extreme smallness of the variations in the period of oscillation. ↗
I love the line of Flaubert about observing things very intensely. I think our duty as writers begins not with our own feelings, but with the powers of observing. ↗