Exodus 25:10

Ark, to contain the tables of the law, as a constant memorial of the alliance made between God and his people, ver. 16. In, or on the side of it, were also placed the rod of Aaron, (Numbers xvii. 10.) and the golden urn, containing manna, Hebrews ix. 3. Hence the pagans perhaps took occasion to keep their secret mysteries in an ark, cista secretorum. (Apul. Met. 2.) (Calmet) --- The ark was three feet nine inches long, two feet three inches high, and as much in breadth. (Haydock)