Though there is Scriptural warrant for preternatural origin and purpose of dreams, e.g., Jacob's ladder dream (Genesis 28) and that of Saint Joseph on the flight of the Holy Family into Egypt (Matthew 2), still dreams generally arise from merely natural causes and convey no knowledge beyond what could be obtained from other natural sources. Dreams may at times profitably be the subject of psychological investigation, but even here their value can be exaggerated or abused, as in Freudian systems.