Lady Agnew's personality engages in endless elusive play against her social type. Sargent has made her face almost schematic, yet within the regularity there is slight departures, nuances whose faintness blends nicely with the sitters languid pose. Lady Agnew's face seems all possibility, and consciously so. The moment of the right side of her lips look slightly drawn back, as if in doubt or weariness, the left side seems almost to smile. And, as if to insist on her control of this ambivalence, her eyes are oddly calm.
(http://hoocher.com/john_singer_sargent/john_singer_sargent.htm)