Summary: Only the spotless, perfect lamb was chosen to be the sacrice, therefore the blessing in the blemish is life!
17. And the Lord spake unto Moses, saying,
18. Speak unto Aaron, and to his sons, and unto all the children of Israel, and say unto them, Whatsoever he be of the house of Israel, or of the strangers in Israel, that will offer his oblation for all his vows, and for all his freewill offerings, which they will offer unto the Lord for a burnt offering;
19. Ye shall offer at your own will a male without blemish, of the beeves, of the sheep, or of the goats.
20. But whatsoever hath a blemish, that shall ye not offer: for it shall not be acceptable for you.
21. And whosoever offereth a sacrifice of peace offerings unto the Lord to accomplish his vow, or a freewill offering in beeves or sheep, it shall be perfect to be accepted; there shall be no blemish therein.
22. Blind, or broken, or maimed, or having a wen, or scurvy, or scabbed, ye shall not offer these unto the Lord, nor make an offering by fire of them upon the altar unto the Lord.
23. Either a bullock or a lamb that hath any thing superfluous or lacking in his parts, that mayest thou offer for a freewill offering; but for a vow it shall not be accepted.
24. Ye shall not offer unto the Lord that which is bruised, or crushed, or broken, or cut; neither shall ye make any offering thereof in your land.
Romans 6:23 (quickview)  tells us that the price that must be paid for sin has always been death. Beginning with the coat of skin that God made for Adam and Eve in the garden, some animal had to die so that their nakedness (sin) could be covered.
In Leviticus God gives Moses the specific instructions for:
The Passover Lamb
The Lamb of Atonement
The Sin Offering
The Oblation of Vows
The Thanksgiving Offering
The Freewill Offering
The Peace Offering
The Trespass Offering
The Cleansing of Lepers
The Wave Offering
The Purification of the Unclean
The First Fruits Offering
The Offerings of Appointed Feasts
All Burnt Offerings
...all of the folling had one common denominator. Reguardless of which animal was to be sacrificed it was to be spotless, without blemish.
Webster describes a blemish as:
1. A mark that mars the appearance, as a stain, spot, scar, etc.
2. Any flaw, defect, or shortcoming
Without a doubt all of humanity is blemished. We have our scars, our flaws, our defects, our shortcomings. I