Jacob's thigh was disabled by the Angel, to show the patriarch that his prevalence was through his faith and prayer, not through force, Genesis 32:25-31. Smiting the thigh was a gesture of self-condemnation and grief, Jeremiah 31:19 Ezekiel 21:12.
In general, a datum is a base elevation used as a reference from which to reckon heights or depths. A tidal datum is a standard elevation defined by a certain phase of the tide.
This confuses many people. In simple terms: A datum is a system which allows the location of latitudes and longitudes (and heights) to be identified onto the surface of the Earth-ie onto the surface of a âroundâ object.