And the stork, the heron after her kind, and the lapwing, and the bat.

Jamieson-Fausset-Brown Bible Commentary

19. the stork-a bird of benevolent temper and held in the highest estimation in all Eastern countries; it was declared unclean, probably, from its feeding on serpents and other venomous reptiles, as well as rearing its young on the same food.

the heron-The word so translated only occurs in the prohibited list of food and has been variously rendered-the crane, the plover, the woodcock, the parrot. In this great diversity of opinion nothing certain can be affirmed regarding it. Judging from the group with which it is classified, it must be an aquatic bird that is meant. It may as well be the heron as any other bird, the more especially as herons abound in Egypt and in the Hauran of Palestine.

the lapwing-or hoopoe; found in warm regions, a very pretty but filthy species of bird. It was considered unclean, probably from its feeding on insects, worms, and snails.

the bat-the great or Ternat bat, known in the East, noted for its voracity and filthiness.

Matthew Henry's Concise Commentary

11:1-47 What animals were clean and unclean. - These laws seem to have been intended, 1. As a test of the people's obedience, as Adam was forbidden to eat of the tree of knowledge; and to teach them self-denial, and the government of their appetites. 2. To keep the Israelites distinct from other nations. Many also of these forbidden animals were objects of superstition and idolatry to the heathen. 3. The people were taught to make distinctions between the holy and unholy in their companions and intimate connexions. 4. The law forbad, not only the eating of the unclean beasts, but the touching of them. Those who would be kept from any sin, must be careful to avoid all temptations to it, or coming near it. The exceptions are very minute, and all were designed to call forth constant care and exactness in their obedience; and to teach us to obey. Whilst we enjoy our Christian liberty, and are free from such burdensome observances, we must be careful not to abuse our liberty. For the Lord hath redeemed and called his people, that they may be holy, even as he is holy. We must come out, and be separate from the world; we must leave the company of the ungodly, and all needless connexions with those who are dead in sin; we must be zealous of good works devoted followers of God, and companions of his people.
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