I Make Myself Invisible in Articles by Aleister Crowley.

“This was the beginning of an art which stood me in good stead in Calcutta years later. While I was walking through the native quarter at night I was set upon by robbers.

When I saw a knife flash I thought it was beyond a joke; pinioned though I was, I managed to fire my revolver. Hundreds of natives aroused by the report rushed out to seek me, but I was able to walk unperceived through the midst of them, and make my escape.” [via, also]