Purpose Of Ablution
Since the whole religion revolves around Tazkiya (Purification of body, meal and soul), therefore , in order to achieve that Tazkiya of body specifically, requirements like wudu / ablution, Cleaning the body after excretion and urination, Bathing after the menstrual and the puerperal periods, Ghusl al-janabah are required of a Muslim. Though the primary objective is cleanliness in all these activities, but a realistic balance has been struck between the level of effort required with that of the primary objective. Some requirements of cleanliness are absolute in their nature like Ghul al-janabah for example, but some are less absolute like wudu but nevertheless, it serves both as a reminder of hygiene as well as helps us achieve hygiene to some extent. And in case of extreme difficulty, both requirements have been removed, both of Ghul al-janabah and that of wudu, and only tayammum is required of the individual, to at least serve as a reminder of the primary objective and with the will to go back to better form of hygiene achieving methods as soon as situation returns to normal. Therefore, the primary objective remains constant, but the modes to achieve that have been set in a realistic manner so that not to cause too much burden on Muslims in their capacity as humans.