Next to Godliness
Q. What does it mean to be clean? The minimal and correct use of food and intercourse can be useful for our lives, but is it possible to make maximum use of these desires and still be clean?
A. Thanks for your question, but I'm afraid you're going to have to be a little more specific about what you mean by cleanliness.
We often use the terms "clean" and "unclean" to refer to spiritual purity and impurity (taharah and tumah, respectively). These have nothing to do with physical cleanliness. Something can be spotless but ritually unclean, or filthy but ritually clean. Spiritual impurity is an immeasurable condition that would mostly affect one's ability to enter the Temple and to eat from sacrifices – in other words, it doesn't have a lot of practical application nowadays. The exception is the way that one particular form of tumah impacts a couple's marital relations from time to time. This is often referred to as observing "the laws of family purity."
"Clean" could also refer to cleanliness from sin. The last Mishna in the tractate of Sotah tells us that "zeal leads to cleanliness, cleanliness leads to purity, purity leads to abstinence, abstinence leads to holiness, holiness leads to humility, humility leads to fear of sin, fear of sin leads to piety...." "Cleanliness" in this context means clean of sins.
Of course, there's also physical cleanliness, which is necessary for prayer and other religious obligations (as well as for hygiene, of course). While certain natural functions, like excretion and reproduction, are "unclean," we wouldn't advise abstention from eating and reproducing, though we do advocate a certain degree of moderation in such matters. That seems to jibe with your idea about correct use of such things.
However, it must be noted that "moderate" is not the same as "minimal." While we're not big fans of hedonism, we also don't advocate asceticism. Too much of a good thing can be bad; the same is true of too little. (See the Ramban in Shemoneh Perakim chapter 4 that the reason a nazir [nazirite] brings a sin offering is for depriving himself of wine altogether rather than enjoying it in moderation.)
So, there are lots of types of cleanliness for us to work on, but none of them would require total (or near-total) abstention from all of life's pleasures.
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