The next jewel in this string of parables is the Pearl of Great Price.
It reads: "Again, the Kingdom of Heaven is like unto a merchant man, seeking goodly pearls: Who, when he had found one pearl of great price, went and sold all that he had , and bought it."
Since verse 51 says: "Have ye understood all these things?" It is apparent that all of these parables are somehow related. If this is so, we can understand this one as following the previous one. A pearl is a valuable treasure when it is large and flawless. A large pearl takes more time to form than a small one; and the fewer flaws it contains, the more it is worth. From these observations we may conclude that whatever this pearl represents, it must be large, flawless, and must have taken a long time to form. Other ideas come to mind with this particular gemstone. First of all, a pearl forms from an irritant such as a piece of sand. Secondly, this process takes place inside of an oyster, which means that its formation must have been unseen, or in secret. They are, moreover, with few exceptions, white--a color which usually signifies purity.
If we assume that this merchant is like the man that bought the field in the previous parable, and the pearl likewise represents the treasure, then the pearl is the mystery of the lost Scriptures. This mystery would only be revealed at the conclusion of the age, and would hence fit the requirement of being formed over a long period of time. And since the number of apocryphal books (as well as the canonical ones) is rather large, the analogy holds, since a large pearl is worth more than a small one. It must also be noted that the merchant, though looking for pearls, only bought the one. Instead of seeing all of these Scriptures as separate both from the canon and from each other, he sees only one thing, and thus we may conclude that they are a unity; that God inspired them all to work together. The great price that Jesus paid for our salvation is apparent when we consider that the entire heavens and the earth, and the totality of all things contained therein have all had to work together for all ages to achieve this end; to save us from our depravity and unbelief.
This parable also has a 'twin' in the Gospel of Thomas. Saying 76 reads: "The (Father's) imperial rule is like a merchant who had a supply of merchandise and then found a pearl. That merchant was prudent; he sold the merchandise and bought the single pearl for himself. So also with you, seek His treasure that is unfailing, that is enduring, where no moth comes to eat, and no worm destroys."
The supplementary information added to the end in this particular version solidifies the idea that 'pearl' and 'treasure' are interchangeable in these examples. This treasure is 'unfailing', which reinforces the idea of perfection previously stated; and the word 'enduring' calls to mind the idea that such a pearl would take a long time to form.
It is significant that it reads: "...he sold the merchandise and bought the single pearl for himself," as opposed to the several or many pearls he could have otherwise purchased. Matthew 13:45 states that he was "seeking goodly pearls", so it is likely that his specialty was gemstones, so the merchandise that he sold was probably other gems--maybe even other pearls. If these other, lesser gems represent his theological assumption that apocryphal books are separate, and distinct both from the Scriptures and each other, then they would be seen as many and of comparably little worth. But upon a sudden flash of insight, he comes to see their value to him as more than the sum total of their parts, all of them apart from each other do not compare with the singular pearl he could exchange them for.