Some people argue that these two rules refer only to gold and silver but such a view is indefensible. Other people try to get around this rule by saying that it is only a minor rule, inapplicable to monastic life today. Monks, there are these four stains because of which the sun and moon glow not, shine not, blaze not. Even so, monks, there are these four stains because of which monks and priests glow not, shine not, blaze not. The non-acceptance of money has always been one of the fundamental observances of those who have left the world.
Money is the measure of wealth and to most people material wealth is the goal of life.
In the renunciation of money by monks and nuns, they emphatically demonstrate their complete rejection of worldly pursuits. At one stroke they set themselves significantly apart from the vast majority of people and thus become a constant reminder to all that a life based on the struggle to accumulate money is not the only way to live. Through giving up money they give up much of their power to manipulate the world and to satisfy their desires. Anguttara Nikaya , volume 2, page 53. Samyutta Nikaya , volume 4, page 326.