The Concept of Instrumentality
Human Instrumentality, in its most basic form, is the elimination of opinions and individual thought from the Human Race. Caused by the meeting of Adam and one of his Angels, the resulting explosion of energy would then revert all of Humanity into a sea of LCL, the basic state of their soul. All of this LCL is then mixed together, resulting in all of the Human Race being linked through their thoughts, ideas, and being. Therefore, at the cost of all individual existance, the world would be eliminated of all conflicts, all arguements, and all diverging opinions.
The Human Instrumentality Project was first ever mentioned in the Lost Chapter of the Human Instrumentality Project in the possession of SEELE. The Scrolls told of the two coming catastrophes, the first summoning the Angels, and the second bringing about Instrumentality, the next stage of evolution for humanity.
The warning in the Dead Sea Scrolls was ignored, though, until a giant creature fitting the Sea Scrolls description of the angels was found in Antarctica. In an attempt to excavate the angel, an explosion resulted, and the first of the two catastrophes mentioned in the Scrolls came to be.
SEELE, realizing that the scrolls were in fact telling the truth, created the GEHRIN Organization, later known as NERV, to stop the angels from reaching the original angel found in Antarctica. To do so would then cause the Third Impact, and all of the planet would have been eliminated.
However, the Sea Scrolls also told of another possible Third Impact, one which would benefit humanity. This other project, the destruction of all of the angels, was also given to NERV, and SEELE then began creating knew defense Systems, The Evangelions.