Be peaceful within yourself, and heaven and earth will be at peace with you. Be diligent to enter into the treasury that is within you, and you will see the Treasury of Heaven: for these are one and the same, and with one entry you will behold them both. The ladder of the Kingdom is within you, hidden in your soul. Plunge deeply within yourself, away from sin, and there you will find steps by which you will be able to ascend.

St Isaac the Syrian
Ascetical Homilies