The ambassador is giving King Narai of Siam a letter from King Louis XIV. In spite of some court protocol having been
changed for the ambassador (not having to take off his shoes, for example), the ambassador is not pleased that he can’t
hand the letter directly to the King, in the western manner, which is why he’s not holding the tray higher. The man on the
floor lifting his hand is beseeching the ambassador to lift the tray higher to make it easier for the king to pick up the letter.