Rabbi Samson Raphael Hirsch: Vayeitzei: The Foundation Stone
“And Jacob rose up early in the morning and took the stone that he had placed his head and set it up as a Monument and poured oil on top of it.” (Genesis 28:18) A ‘Matzeiva’ – monument – consists of a single stone. Mizbei’ach – Altar – is an elevation built up by many stones. Matzeiva is presented by nature, Mizbei’ach is made by man. Before the giving of the Torah God’s rule was manifest primarily only in the ways of nature and in Man’s fate, accordingly in what Man gets from the Hand of God.
A Matzeivah corresponds to that, a stone taken from God’s creation as a memorial for something that He has done.
But with the giving of the Torah, God wishes to be revealed, not so much in what Man receives from Him, as in what Man does with what he gets from Him; not with God’s gifts but with Man’s deeds is God to be glorified. That indeed is the purpose of Torah, and why since Sinai, Matzeivah is rejected. (Rabbi Samson Raphael Hirsch, Commentary to the Torah)
Yaakov transformed the Monument into a Mizbei’ach when he poured the oil. The Stone became a symbol of the role of Man to glorify God with deeds, and to not accept being a receiver with nothing to offer back to the Creator.
Each time we are granted the gift of a new insight into Torah or Service of God we are connecting with that moment when Yaakov Avinu transformed the monument into a Mizbei’ach – the moment of Revelation at Sinai – a draw our spiritual sustenance from the Foundation Stone.