Translated by Frederick Crombie.
Book I, II, III, IV, IV (Literal)
Origen ON THE PRINCIPLES
1. All who believe and are assured that grace and truth were obtained through Jesus Christ, and who know Christ to be the truth, agreeably to His own declaration, "I am the truth,"  derive the knowledge which incites men to a good and happy life from no other source than from the very words and teaching of Christ. And by the words of Christ we do not mean those only which He spake when He became man and tabernacled in the flesh; for before that time, Christ, the Word of God, was in Moses and the prophets. For without the Word of God, how could they have been able to prophesy of Christ? And were it not our purpose to confine the present treatise within the limits of all attainable brevity, it would not be difficult to show, in proof of this statement, out of the Holy Scriptures, how Moses or the prophets both spake and performed all they did through being filled with the Spirit of Christ. And therefore I think it sufficient to quote this one testimony of Paul from the Epistle to the Hebrews,  in which he says: "By faith Moses, when he was come to years, refused to be called the son of Pharaoh's daughter; choosing rather to suffer affliction with the people of God, than to enjoy the pleasures of sin for a season; esteeming the reproach of Christ greater riches than the treasures of the Egyptians."  Moreover, that after His ascension into heaven He spake in His apostles, is shown by Paul in these words: "Or do you seek a proof of Christ who speaketh in me?" 
 John xiv. 6.
 [Here, and frequently elsewhere (some two hundred times in all), Origen, in his extant works, ascribes the authorship of the Epistle to the Hebrews to St. Paul. Eusebius (Ecclesiastical History, vi. 25) quotes Origen as saying, "My opinion is this: the thoughts are the apostle's; but the diction and phraseology belong to some one who has recorded what the apostle said, and as one who noted down what his master dictated. If, then, any Church considers this Epistle as coming from Paul, let it be commended for this; for neither did those ancient men deliver it as such without cause. But who it was that committed the Epistle to writing, is known only to God."]
 Heb. xi. 24-26.
 2 Cor. xiii. 3.
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Reference address : http://www.ellopos.net/elpenor/greek-texts/fathers/origen/principia.asp