Daniel 6:17 "Then a stone was brought and laid on the mouth of the den, and the king sealed it with his own signet ring and with the signets of his lords, that the purpose concerning Daniel might not be changed."
The king sealed it with his own "signet ring"
An Emblem of Authority
Dan 6:17 "Then a stone was brought and laid on the mouth of the den, and the king sealed it with his own signet ring and with the signets of his lords, that the purpose concerning Daniel might not be changed."
The "signet ring," also known as a "seal" comes from the Hebrew word "hotam" and the Greek word "sphragis" and was used universally in the ancient world. It was a portable instrument used much like we use a signature today, but much more important. They would seal or stamp a document, or the door of a house, or a tomb, etc. It was also an emblem of authority.
Authentic ancient documents contain seals. The way they did it was to cover it with "ink" and press it. Most often it was attached to a ring and worn on the finger or else it hung from the neck on a string or on the arm. Many shapes have been discovered ranging from cylindrical, square and round, to oval and pyramid shape. The engraver was a common occupation in ancient times.
The ancient Egyptians most familiar form of a signet ring was made of stone, round on one side and flat on the other. The flat side was very elaborate and bore the inscription, usually containing symbols, hieroglyphic letters, and the scarabaeus or sacred beetle. The beetle was worshipped by the Egyptians as well as the Phoenicians and other cultures. Examples of these seals are known as far back as the Fourth Dynasty, c. 2550 B.C. Sometimes they were made of blue pottery or porcelain or a lump of clay, impressed with a seal and attached to the document by strings.
In ancient Mesopotamia around 3500 BC the cylinder seal was first used. At Uruk (Erech in the Bible, Gen. 10:10) which is modern Warka, two small square tablets of gypsum plaster were uncovered that contained impressions of cylinder seals. They were apparently rolled across soft clay, a package or jar was sealed with wet clay and the seal was rolled over it.
Soon after, the Persians introduced the stamp seals. The Uruk seals display amazing beauty. Henri A. Frankfort, formerly research professor of oriental archaeology at the Oriental Institute of the University of Chicago, made monumental studies in the development of the cylinder seal from the prehistoric period to the dynasties of ancient Sumer and Babylon down to the Persian period. See Frankfort's book, Cylinder Seals where he discusses his research of over 1000 discovered seals.
One interesting seal is the Lapis Lazuli seal of Queen Puabi (or Shubad) uncovered by Woolley at Ur. Also the well-known seal of Darius the Great displays the king in his two-wheeled chariot between two date palms.
"Cylinder seals found in ancient Mesopotamia were incised on various hard surfaces including gold, silver, rock crystal, blue chalcedony, carnelian, marble, ivory, jasper, glazed pottery, and simple baked clay. Often seals contain both pictures and written material. Jar-handle seals were also common from c. 2500 B.C. These were used not only in signing Babylonian clay documents but in safekeeping jars containing valuable papers or commodities for shipment to distant lands. A cloth was placed over the neck of the container, soft clay smeared on top of the binding cord, and the cylinder rolled over the wet clay. If the seal was undisturbed at its destination, the merchandise was safe." -Merril F. Unger
The Hebrews used the seal as an ordinary piece of equipment. It was mentioned throughout the Bible in many different time periods. Even on the breastplate of the high priest there were engraved gems of the twelve tribes.
Christians are Sealed by the Holy Spirit
There are many metaphors in the Bible using the "seal" or "engraving" of the Lord as something that is set and permanent. Christians are forever "sealed with the Holy Spirit of promise" Eph. 1:13.
This verse we are discussing teaches us much of how things were done in ancient times. The king (Darius) was committed to keep his word, and he sealed the stone which imprisoned Daniel even though it was against the king's wishes. Darius even fasted the whole night for a miracle concerning the Jewish God, Yahweh, to somehow preserve Daniel's life.
Bibliography on Ancient Customs
The Art of Ancient Egypt, Revised by Robins, 272 Pages, Pub. 2008