In contrast to other nations and races of the world, which grew in number over the years, the Jewish nation has always been relatively small, as though proclaiming to the gentiles around it: “What matters is quality, not quantity.”

Historians estimate that at the time of the Second Temple, the nation numbered approximately four million.  At the time of the Spanish Expulsion, in 1492, there were only one and a half million Jews in the world.  Up until the beginning of the nineteenth century, the rate of natural increase in numbers was extremely slow. 

All this was foretold in the Bible.  G-d revealed to the Jewish People that because of their sins, the nation would shrink in size rather than becoming as numerous as the stars in the heavens.

You will be left few in number, instead of having been like the stars of heaven in abundance, for you will not have hearkened to the voice of the L-rd, your G-d.

Deuteronomy 28:62

Despite its relatively small numbers, the People of Israel is eternal, as stated by Isaiah the Prophet:

“Thus said the L-rd: Just as when the wine is found in a cluster, and someone says: ‘Do not destroy it, for there is a blessing in it,’ so will I do for My servants, not to destroy everything.

Isaiah 65:8

Just as wine does not go bad with time, but improves with age, so, too, the Jewish people.  A vintage wine, aged for decades, is available in limited quantities; so, too, the Jewish People has remained limited in number.