Answer:
1) The permanent method to destroy data from a hard disk would be to puncture the hard disk meaning to drill a hole into the disk.
2)Use software like Boot and nuke.
Explanation:
In order to increase the life span of hard drives the data that we store is distributed evenly over many sectors that are not adjacent. In traditional methods of erasing data such as formatting the disc the data can be reconstructed by using sophisticated tools available to various agencies, making our data vulnerable to reconstruction and use.
Physically damaging the hard disk renders the disk useless thus there is no way by which the data can be reconstructed.
Many safe and secure software are also avaliable like Boot and Nuke to destroy the data.
I believe the answer is: Sigmund Freud
He was the first psychologist that popularised the idea of subconscious, which is a state of mind that exist underneath our normal thought which might influence our behaviour without being realised.
This concept of unconscious motives bring us one step closer to understanding the cause of many psychological disorders such as psychopathy or multiple personalities.
Its important so that no one person has to much power