A seal was a simple device used to make an impression upon a soft material, such as wax or clay. When the substance hardened, a durable imprint remained. Seals have been used for thousands of years throughout the ancient world. They were made of metal or stone, including various precious gems. There are many fine examples to be found in private collections and museums all around the world. Seals were originally in the form of a cylinder that was rolled upon the surface (example in photo), but they later took the form of a ring worn on a finger (the original Hebrew word of the Scriptures translated as seal, pronounced koe-thawm, means a signature ring, or signet - the original meaning of signature meant a seal), or a stamp that was carried in a necklace or cord around the waist.
Seals were used extensively during Bible History for two primary purposes. In a royal or official command:
"in the name of king Ahasuerus was it written, and sealed with the king's ring." (Esther 3:12 KJV)
"So she [i.e. Jezebel] wrote letters in Ahab's name, and sealed them with his seal, and sent the letters unto the elders and to the nobles that were in his city" (1 Kings 21:8 KJV)
Note: As this case shows, seals were sometimes used fraudulently i.e. Jezebel forged the king's signature.
To ratify or authenticate an agreement:
"So I took the evidence of the purchase, both that which was sealed according to the law and custom, and that which was open: And I gave the evidence of the purchase unto Baruch" (Jeremiah 32:11-12 KJV)
"we make a sure covenant, and write it; and our princes, Levites, and priests, seal unto it." (Nehemiah 9:38 KJV)
The use of seals is found in the New Testament in connection with the burial of Jesus Christ (Matthew 27:66). The Tomb was sealed by the Pharisees and chief priests to prevent anyone from stealing the body (Matthew 27:63-64). This was most likely done by extending a rope across the stone and attaching it at both ends with sealing-clay.
Sealing was also used in a figurative sense:
"Labour not for the meat which perisheth, but for that meat which endureth unto everlasting life, which the Son of man shall give unto you: for Him hath God the Father sealed." (John 6:27 KJV)
"In whom ye also trusted, after that ye heard the Word of Truth, the Gospel of your salvation: in whom also after that ye believed, ye were sealed with that Holy Spirit of promise, which is the earnest of our inheritance until the redemption of the purchased possession" (Ephesians 1:13-14 KJV)
"for the seal of mine apostleship are ye in the Lord." (1 Corinthians 9:2 KJV)
"And I heard the number of them which were sealed: and there were sealed an hundred and forty and four thousand of all the tribes of the children of Israel." (Revelation 7:4 KJV)
Some of the most spectacular events of Bible Prophecy involve The Seven Seals of the Book Of Revelation.
Fact Finder: Was the understanding of the prophecy in the Daniel "sealed" until the time of the end?
See also Nebuchadnezzar's Dream