Both Uses

illustrate
in
And The Mountains Echoed
(Edited)

The way her hand bent at its slender wrist reminded me of an illustration I had once seen in a glossy book of poems of a long-lashed woman with flowing dark hair lying with her lover in a garden, offering him a cup of wine with her pale delicate fingers.
Chpt 4 *

illustration = picture
The case will be used next week for Peer Review, a monthly video conference watched by all the facilities during which mistakes by physicians, who remain anonymous, are used to illustrate learning points.
Chpt 5 *

illustrate = help make clear

Definitions:

(1) (illustrate as in: as illustrated by this example)
to help make clear -- typically by example
(2) (illustrate as in: an illustrated children's book)
to draw pictures (or provide photographs) to accompany a book or other writing
(3) (meaning too rare to warrant focus)