"The SOUL, inhabiting the Brain, or acting, where it doubtless does, immediately behind the Optic Nerves, stamps, instantaneously upon the Eye, and Eyebrow, a struck Image of conceiv'd Idea: And that in Fact it does This, and that it does it, in the very Instant of Conception, every Man must every Hour, experience, in his Act, and Attitude, of Thinking; for, no sooner can he set himself to ponder, or intensely meditate, on any Object, than he perceives his Eye, and Brow, imprintedly partaking, and assisting to produce Conception:--If the Image is a pleasing one, the Brow dilates; -- as if to give it Room -- if painfull, it contracts itself, as if it would evade or guard against a half-admitted Object."
— Hill, Aaron (1685-1750)
Text from The Works of the Late Aaron Hill, 4 vols. (London: Printed for the Benefit of the Family, 1753).
Copy at Folger Library also consulted. Aaron Hill, The Art of Acting. Part 1. Deriving Rules from a New Principle, for Touching the Passions in a Natural Manner. An Essay of General Use. (London: Printed for J. Osborn, 1746).