Joshua Reynolds, Portrait of a Woman, Possibly Elizabeth Warren, 1759, Oil on canvas, Kimbell Art Museum

Caption from the museum's website:
The sitter in the Kimbell portrait may be identifiable as the “Miss Warren” who appears in Reynolds’s records as sitting for the artist between January 1758 and May 1759. Often incorrectly identified as Frances Warren, second wife of Sir George Warren, the wealthy member of parliament for Lancaster, she is, in fact, more likely to be his sister, Elizabeth Warren. This portrait is one of Reynolds’s earliest essays in the grand manner, in which beauty and grandeur are achieved by avoiding the particularities of local fashions. Miss Warren’s simple, wrap-around morning gown displays the contours of her figure and lends the portrait a timeless, classical effect. Her idealized form has something of the quality and dignity of sculpture, with smooth, alabaster skin and graceful drapery folds. The proportions of the figure above the high waist are deliberately diminished, while her hips and thighs swell like the oversized urn beside her, perhaps alluding to her female role as a fecund vessel.