The Buddha said that there were four necessities of life — clothing, food, lodging and medicine — and that they have to be treated properly:

“Properly considering the robe, I use it: simply to ward off cold, to ward off heat, to ward off the touch of flies, mosquitoes, simply for the purpose of covering the parts of the body that cause shame.

“Properly considering almsfood, I use it: not playfully, nor for intoxication, nor for putting on weight, nor for beautification; but simply for the survival and continuance of this body, for ending its afflictions, for the support of the chaste life, (thinking) I will destroy old feelings (of hunger) and not create new feelings (from overeating). Thus I will maintain myself, be blameless, and live in comfort.

“Properly considering the lodging, I use it: simply to ward off cold, to ward off heat, to ward off the touch of flies, mosquitoes, wind, sun and reptiles; simply for protection from the inclemencies of weather and for the enjoyment of seclusion.

“Properly considering medicinal requisites for curing the sick, I use them: simply to ward off any pains of illness that have arisen and for the maximum freedom from disease.”

Clothing, food, shelter and medicine are necessary whether one is a lay person or a bhikkhu. The bhikkhu, however, should take a completely balanced stance towards these fundamentals. Advertising and the latest fashion should not draw him, for he should be solely concerned with simplicity and lack of attachment towards things. It seems that the original requisites were ‘basics’ that wandering bhikkhus could conveniently carry around, for example, an alms bowl, three robes, a sitting cloth, a needle-case, and a waist band. However, extra allowances were gradually given as the need arose, for instance, a water filter, a razor and its sheath, the stone and strop for sharpening it and then articles such as an umbrella and sandals. Later the commentaries allowed other similar items.

Extracted from The Bhikkhus’ Rules: A Guide for Laypeople compiled and explained by Bhikkhu Ariyesako.