Rabbi Yannai said: Tefillin require a clean body, like ElishaBa’al Kenafayim (the possessor of wings) … Why is he called Ba’al Kenafayim? Once the Roman’s decreed that whoever put on tefillin would have his brain pierced. Elisha wore them and went out to the marketplace. An official saw him. Elisha ran away, pursued by the official. When the official caught him, Elisha took the tefillin off his head and held them in his hand. He asked: "What is in your hand?" He answered: "The wings of a dove." He opened his hand, and there were dove wings. Ein Ayah:
There is a broad rule that matters of a lesser level that are part of the process of human development precede matters that are of a greater level. The idea is that the lower level is the base for the higher one and, therefore, must precede it.
Tefillin are a special covenant with Israel, a testament to their distinctiveness as a "kingdom of priests and a holy nation," as singled out by the Master of All. Therefore, the path they are to follow and the morality required of them are loftier than that which is required of all other nations and cultures. "He did not do so for all nations, and He did not inform them of the statutes" (Tehillim 147:20).
There is a level of proper behavior in the realm of human dignity and purity of characteristics, which every nation should strive for. This includes a person favoring cleanliness and rectitude in that which can be sensed and felt and in openly hating evil and iniquity. Thus, the seven Noahide Laws are geared toward that aim. In order to achieve natural morality, one does not have to have lofty spiritual aspirations. However, his body should be clean from the filth of evil that can specifically affect predators and wild pigs (a hint at the Romans).
Therefore, in order for one to ascend to the mountain of Hashem to connect to the lofty morality that relates to the elevated sanctity that is possessed in tefillin, one has to have a clean body. In other words, he is building on a base of natural morality, not polluted by bad actions and attributes, which are an abomination to a person in terms of his human image.
Once the natural physical morality is taken care of, a member of Bnei Yisrael who wants Hashem’s name to be called upon him, needs to elevate himself through the depth of lofty sanctity that is revealed by the sanctity and uniqueness of Israel. To "go up to the mountain" of lofty morality, one uses wings, which elevate the spirit of the member of the Jewish nation who already acquired physical correctness. He cannot reach a lofty spiritual level while he is significantly deficient in matters of his natural status. Rather, his ability to withstand difficulties in trying times depends on the connection between his nature and the sacred things for which he strives. The stronger and more connected his spiritual efforts are, the more he will be able to withstand the stormy sea of troubles.
Who is able to fully recognize the impact that tefillin have over him? After all, it can take us far beyond simple levels of morality and have us fly among lofty levels of spirituality. It takes someone who has completed his natural morality and then discerns that despite the good that this entails, the spirit is still waiting for so much more, namely, spiritual morality that emanates from the Torah. Such a person has a clean body and he is an owner of tefillin who also possesses wings. His physical side will not drag him down, and he will find himself to be full of strength even in dangerous times. When he comes face to face with the Roman regime, he is rightly called a possessor of wings, which are a sign of his body’s purity and cleanliness.