Remarkable if it managed to work on just one wire :)
Earth is good to provide a measure of safety and help to prevent electrocution.
Live is usually required and often (always) has some form of interruption device - a switch somewhere in the circuit to turn the light off and on.
See what happens without the Neutral - you never know - but my guess is that you will probably need to connect it if you wish the light to operate.
Peccavi
April 2009