How does Robert K. Massie use imagery in Nicholas and Alexandra?

Example of Imagery:

"Then, for the first time and only time in his life, the Tsar entered the sanctuary to receive the sacrament as a priest of the church. As Nicholas walked up the altar steps, the heavy chain of the Order of St. Andrew slipped from his shoulders and fell to the floor. It happened so quickly that no one noticed except those standing close to the Tsar. Later, lest it be taken as an omen, all those were sworn to secrecy."