the blade until it is perfectly sharp and smooth. After the slaughter, the shochet must check the knife again in the same way to be certain the first inspection was properly done, and to ensure the blade was not damaged during shechita. If the blade is found to be damaged, the meat may not be eaten by Jews. If the blade falls or is lost before the second check is done, the first inspection is relied on and the meat is permitted. In previous centuries, the chalaf was made of forged steel, which was not reflective and was difficult to make both smooth and sharp. Shneur Zalman of Liadi, fearing that Sabbateans were scratching the knives in a way not detectable by normal people, introduced the Hasidic hallaf (). It differs from the previously used knife design because it is made of molten steel and polished to a mirror gloss in which scratches could be seen as well as felt. The new knife was controversial and one of the reasons for the 1772 excommunication of the Hasidim. As of present time, the "Hassidic hallef" is universally accepted and is the only permitted blade allowed in religious communities. Other rules The animal may not be stunned prior to the procedure, as is common practice in non-kosher modern animal slaughter since the early 20th century. It is forbidden to slaughter an animal and its young on the same day. An animal's "young" is defined as either its own offspring, or another animal that follows it around. The animal's blood may not be collected in a bowl, a pit, or a body of water, as these resemble ancient forms of idol worship. If the shochet accidentally slaughters with a knife dedicated to idol worship, he must remove an amount of meat equivalent to the value of the knife and destroy it. If he slaughtered with such a knife on purpose, the animal is forbidden as not kosher. Post-procedure requirements Bedikah The carcass must be checked to see if the animal had any of a specific list of internal injuries that would have rendered the animal a treifah before the slaughter. These injuries were established by the Talmudic rabbis as being likely to cause the animal to die within 12 months time. Today all mammals are inspected for lung adhesions ( "examination of the lung") and other disqualifying signs of the lungs, and most