"Summa Theologica" by Saint Thomas Aquinas

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Man requires more than philosophy in his search for truth ;
certain truths are beyond human reason and are available only because of divine revelation ;
theology,which depends on revealed knowledge,supplements natural knowledge.
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The existence of God can be proved in five ways :
by reference to motion -and the necessity of a first mover-,
by reference to efficient causes -and the necessity of a first cause-,
by reference to possibility and necessity,
by reference to the gradations of perfection in the world,and
by reference to the order and harmony of nature -which suggests an ordering being who gives purpose to the created world-.
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God alone is the being whose nature is such that by reference to him one can account for the fact of motion,
efficient cause,
necessity,
perfection,and
order.
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God's principal attributes are simplicity -for he is noncorporeal and without genus-,
actuality,
perfection,
goodness,
infinitude,
immutability,
unity,and
immanence ;
but the created intellect can know God only by God's grace and only through apprehencion,not comprehension.
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http://sfakianakisalexandros.blogspot.com/2009/09/summa-contra-gentiles-by-saint-thomas.html#
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