The study of numbers: [Genesis 21:29-31 KJV] 29 And Abimelech said unto Abraham, What [mean] these seven ewe lambs which thou hast set by themselves? 30 And he said, For [these] seven ewe lambs shalt thou take of my hand, that they may be a witness unto me, that I have digged this well. 31 Wherefore he called that place Beersheba; because there they sware both of them. "Sheba" means both "7" and "to swear" showing that numbers have spiritual meanings as well.