The Duties of the Heart, by Rabbi Bachye, tr. by Edwin Collins, [1909], at sacred-texts.com
The Proper Study of Mankind is Man
Although it is incumbent upon us to investigate and study the whole universe, so as to understand the wisdom and goodness of the Creator, the subject most necessary to study, as well as the nearest and most obvious, is the evidence of divine wisdom shown in all that concerns the human species. For man is the universe in little (microcosm), and the proximate cause of the existence of the great world (macrocosm). And it is our duty to study the origin of man and his history; his birth, and the composition and structure of his component parts, and the members and organs of his body, their relations to each other, and the functions and purposes of every one of them; and the necessity of his being made as he is, in structure, form, and appearance. And then we
must consider the objects of his being and all his mental qualities and characteristics, and the powers of his soul, and the light of his reason, and all the essentials and accidentals of his being, and his passions and desires, and his relation to the scheme of Creation.
From the standpoint of this study much of the mystery of the universe, and many of the secrets of this world, will become clear to us, because of the likeness of man to the world; and it has been said by some of the wise men that Philosophy is man's knowledge of himself: that is to say, such knowledge of man will enable us to recognise the Creator from the signs of His wisdom displayed in man. This is the meaning of what Job said: "And from my flesh I shall see God."
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The tongue is the pen of the heart, and the messenger of the distant hidden soul.
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In speech one can see the superiority of man over the lower animals.
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It is the fools who think they know everything, and in their pride neglect that study of the world and man, which would compel gratitude to God, and life devoted to His service and the doing of good works.
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When you have studied all that can be known of
the universe, do not think that you know all about the wisdom and power of God. For in the world, we know, God has only manifested just so much of His wisdom and power as were necessary for the good of man. Not according to the reach of His wisdom and power is their manifestation in the phenomenal world (for they are infinite), but in accordance with the needs of His creation and of His creatures.