contamination or grime. Our brain puts these terminologies in context between ourselves and a particular object. E.g. polluted water, dirty cloths etc. Even modern Arabic uses the same words: .قذر ,وسخة ,تلوث
In Quran purity, Tahara, طهارة ,means purity both in spiritual and physical way. However, even the physical purity doesn’t mean cleanness between us and an object directly. Why? Because there is no object what is not the result of Creation of Allah! Therefore, anything what exists in this world doesn’t belong to us directly. All these are deposits which are placed under our responsibility! We are simply the operators of objects which are lent for us in pure condition and our duty is to keep them pure. This logic works also for body, life and thought as well. So, purity includes our wealth, conduct of our lives, education of our children and our behavior with our society.

Remember We made the House a place of assembly for men and a place of safety; and take ye the station of Abraham as a place of prayer; and We covenanted with Abraham and Isma'il, that they should sanctify My House for those who compass it round, or use it as a retreat, or bow, or prostrate themselves (therein in prayer). (Quran 2:125)

The Ka’ba, the House of God. It was the center to which all the Arab tribes resorted for trade, for poetic contests and for worship. It was sacred territory and was respected by friend and foe alike. At certain seasons all fighting was forbidden within its limits and even arm were not allowed to be carried and no war game was allowed to be performed. Like in Cities of Refuge under the Mosaic Dispensation to which manslayers could flee. (Numbers 35:6), or the Sanctuaries in Medieval Europe to which criminals could not be pursued. Mecca was recognized by Arab custom as inviolable for the pursuit of revenge or violence. It was a place of prayer. Even today there is the place where Abraham was supposed to have prayed. It must be held pure and sacred for all times.

However, this purity should be both physical and spiritual. So, this House has to be free of spiritual contamination, Najas, نجس

O ye who believe! Truly the Pagans are unclean; so let them not, after this year of theirs, approach the Sacred Mosque. And if ye fear poverty, soon will Allah enrich you, if He wills, out of His bounty, for Allah is All-knowing, All-wise. (Quran 9:28)

Concerning menstruation of women Quran uses the word Aza ذىً َأ , which means uncleanness in a very tender way. So, it is not sickness, grime or something like that:

They ask thee concerning women's courses. Say: They are a hurt and a pollution: So keep away from women in their courses, and do not approach them until they are clean. But when they have purified themselves, ye may approach them in any manner, time, or place ordained for you by Allah. For Allah loves those who turn to Him constantly and He loves those who keep themselves pure and clean. (Quran 2:222)

Inhabitants of Medina gathered together from different places bringing different customs which were related to marriage, divorce and relation between family members. Islam regulated these customs under one law which matches with the teachings of modern sciences and regulations of modern societies. Also, there is no taboo in Islam. Quran discloses even the most intimate subjects what can occur between man and woman. The next ayas are instructions for establishing healthy family and social life. Therefore, basic principles had to be clarified for all members of Umma:

• Women’s course or menstruation is not a disease. It serves for purifying women.
• Sexual act is like tilling the soil and seeding. It is acceptable if the aim of sex is procreation offsprings or seeking each other’s pleasure by allowed way. Oral or anal sex where not the “tilth” and “fertile soil” is the objective is prohibited.

Before you establish prayer, you must purify yourself. If you are in a state of impurity you have to take a bath. Here Quran uses Junban to express impurity which means encrustation what sedimented on your souls and bodies:

O ye who believe! when ye prepare for prayer, wash your faces, and your hands (and arms) to the elbows; Rub your heads (with water); and (wash) your feet to the ankles. If ye are in a state of ceremonial impurity, bathe your whole body. But if ye are ill, or on a journey, or one of you cometh from offices of nature, or ye have been in contact with women, and ye find no water, then take for yourselves clean sand or earth, and rub therewith your faces and hands, Allah doth not wish to place you in a difficulty, but to make you clean, and to complete his favour to you, that ye may be grateful. (Quran 5:6)

These are the essentials of Wudu, or ablutions preparatory to prayers, 1. To bath the whole face in water, and 2. Both hands and arms to the elbows, 3. With a little rubbing of the head with water (as the head is usually protected and comparatively clean), and 4. The bathing of the feet to the ankles. In addition, following the practice of the Prophet, it is usual first to wash the mouth, and the nose before proceeding with the face, etc. See: 4:43. Ritual impurity arises from sex pollution. It needs bathing the whole body. This is Tayammum, or wiping with clean sand or earth where water is not available.

Regarding any contact with Quran the physical and spiritual purity is prescribed:

Which none shall touch but those who are clean: (Quran 56:79)

We could continue the examples indefinitely. Tahara is a large chapter of Islam which fills volumes. It includes use of wealth, purity of foodstuff, satisfaction of our soul etc. My intention here was only to demonstrate that we cannot become pure if we look at the things around us with our present comprehension. If you lend your car you expect that you get it back in good condition. Even Allah (SWT) lent for you the globe, your environment, your wealth and your life. He expects that you keep it all in the same condition of Tahara as you have got them.