"Edge also implies what Ben Graham....called a margin of safety. You have a margin of safety when you buy an asset at a price that is substantially less than its value. As Graham noted, the margin of safety 'is available for absorbing the effect of miscalculations or worse than average luck.' ...Graham expands, "The margin of safety is always dependent on the price paid. It will be large at one price, small at some higher price, nonexistent at some still higher price.""