And Jacob dreamed that there was a ladder set up on the earth, and the top of it reached to heaven; and behold, the angels of God were ascending and descending on it! And behold, the LORD stood above it and said, “I am the LORD, the God of Abraham your father and the God of Isaac …” (Genesis 28:12-13)
“Be at peace with your soul and heaven and earth will be at peace with you. Endeavor to enter the treasury within you and you will see that treasury which is in heaven. The former and the latter are one and through a single entrance you will see both of them. The ladder of that kingdom is hidden within you, within your soul. Dive away from sin into yourself and you there you will find the steps by which you may ascend.” (St. Isaac of Nineveh, On Ascetical Life, p. 34)