In Gen. 49.10 Jacob gives the prophecy that the Messiah would come from the line of Judah, that the scepter would be His. The term Jacob uses is “Shiloh.” This term’s meaning according to the standard Hebrew Lexicon (Brown, Driver, Briggs): He whose it is. Or, in other words, “the rightful owner.” Another meaning also can mean Pacificator (Maker of peace, or in this case breaking the enmity between God and men). It has long been associated in Jewish Theology as the indicator of the Messiah.
An amazing collocation of the term Shiloh is developed when the place where the Tabernacle is located after Israel’s entry into the promised land (Josh. 18.1ff) is named “Shiloh.” The Israelites named the place where God’s people gathered to observe their required festivals and sacrifices “Shiloh.” So for them the Messiah and the sacrificial system were linked intrinsically. So, in a redemptive sense, Israel had in mind initially under Joshua the concept of The promised Messiah with the sacrifices at the Tabernacle which were instituted by God to Moses under The Old Covenant.
During the High Priesthood of Eli the Ark of the Covenant was captured and visited judgement upon the Philistines who sent it back to Israel. David later was instructed (or inspired) to locate the Ark and Tabernacle worship in the conquered Jebusite city which became known as Jerusalem. The Jewish Encyclopedia, who are not Christian, note the water source that feeds the city and sustained it whenever it was besieged: A conduit, in which was discovered the Siloam inscription, led to it from the Fountain of the Virgin (‘Ain Sitti Maryam), and through the outer part of the Moriah to a pool in the Tyropœon valley; and it was probably to this conduit that Isaiah alluded in speaking of the “waters of Shiloah that go softly.”
Isaiah (8.5-8) rebuked the Israelites in his day because they didn’t trust the gentle flowing waters of Shiloah (a reference to divine assistance and, ultimately the promised Messiah) therefore a torrent in the army of Assyria would sweep them away instead (the Northern Israel Kingdom with its calf idols which were set up to rival the legitimate sanctuary at Jerusalem). This flood from Assyria would then rage into Judah because of the unfaithfulness of The Southern Kingdom also. Though the towns of Judah would be captured and Hezekiah forced to pay the Assyrian King tribute for a time, Jerusalem would not see the Assyrian inside its walls according to Lord’s promise. Also, because of the denigration of the Lord by the Assyrians, 185,000 would die by some sort of a plague which is attested in Greek sources as well as the bible.
These “cool waters of Shiloah” of the book of Isaiah are the “pool of Siloam” in the New Testament. The whole of chapter 9 in John’s Gospel records the crucial incident of Jesus applying His saliva and earth to a man’s eyes born blind. Jesus told the man to go down to Siloam to wash the mud from his eyes and the man received sight for the first time. This event precipitated the final conspiracy of the Pharisees since Jesus performed this miracle on the Sabbath. The parenthetical note in John signifies the meaning then during the current era of Siloam as “sent.” This verbal idea complements and applies the noun form of Old Testament usage of “Messiah.”
So, this vital stream which sustains Jerusalem and its Temple flows around Mt. Moriah from the “fountain of the virgin.” Jesus used it to reference the plan of God sending His Son as a propitiation for humanity’s healing.