The number three in the Bible represents completeness. That's why Jesus rose on the third day after the Crucifixion -- his transformation was complete. It's why Elijah stretched himself on the dead child three times, why Jonah was in the belly of the fish for three days, why the Lord called Samuel three times, and many more. It's also reflected in the fact that there are three levels of heaven, three levels of hell, three levels to human life and, ultimately, three aspects of the Lord Himself: Father, Son and Holy Spirit.

720. 'Pairs of each' means that in relation to goods they are unholy. This becomes clear from the meaning of that number. A pair or two means not only a marriage (and when the heavenly marriage is meant it is a holy number); it also has the same meaning as six. That is to say, two relates to three in the same way that the six days of labour do to the seventh or holy day of rest. This is why in the Word 'the third day' takes on the same meaning as 'the seventh', and embodies almost the same, the reason being that the Lord's resurrection took place on the third day. This also is why the Lord's Coming into the world and into glory, and also every coming of the Lord, is described by the third day, as well as by the seventh day. The two days which go before therefore are not holy, but in relation to the third are unholy, as in Hosea,

Come and we will return to Jehovah, for He has wounded and will heal us; He has stricken and will bind us up; He will revive us after two days, on the third day He will raise us up, and we shall live before Him. Hosea 6:1-2.

And in Zechariah,

It will be in all the land, said Jehovah, that two parts in it will be cut off and breathe their last, and a third will be left in it. And I will lead the third part through the fire, and I will refine them as one refines silver. Zechariah 13:8-9.

And Psalms 12:6 speaks of silver being purest when it has been purified seven times. These quotations show that just as 'sevens of each' did not mean sevens of each but things that are holy, so 'pairs of each' does not mean two of each but those which in relation to the holy are unholy. Accordingly the meaning is not at all that unclean beasts, or man's evil affections, in relation to clean beasts, or goods, were fewer by a ratio of two to seven; for with man evils far outnumber goods.