Caesar Watches the Merchant from Iran

From D8.1.4, Shapur Goes to Rum and Is Captured by Caesar. It illustrates D8.1.4.44–51:

D8.1.4.44
He bade them set the board and bring the wine;They decked the hall and made the palace shine.
D8.1.4.45
In Rum there lived a man of Iran’s kind,World-traveled, but unjust and harsh of mind.
D8.1.4.46
He said, “Great Caesar, hear my secret word;I bring you news that you have never heard.
D8.1.4.47
He takes our gold for silks and costly things,But he is Shapur, lord of Iran’s kings.
D8.1.4.48
In speech, in face, in grace, in every sign,I know Shapur, the Shah of Iran’s line.”
D8.1.4.49
When Caesar heard, amazement darkened him;He stared at Shapur, troubled, stern, and grim.
D8.1.4.50
He set a guard, but told no other ear,And kept the secret hidden from all here.
D8.1.4.51
When Shah Shapur rose drunken from the wine,Still Caesar watched his face for every sign.