Inspiration

Isn't it one of lifes oddities that inspiration rarely travels alone? One little spark often leads to another and then another and before you know it there's a whole fire of inspiration crackling away where previously there was only a barren space.
How to get the first spark is a mystery in itself. Does it start with an external event? Does your imagination suddenly have a spurt of energy? If you were in a dark room without stimulae would inspiration desert you? Hmmmmmm.