Origen De Princ., 4.2.2

2. Now the reason why all those we have mentioned hold false opinions and make impious or ignorant assertions about God appears to be nothing else but this, that scripture is not understood in its spiritual sense, but is interpreted according to the letter.  On this account we must explain to those who believe that the sacred books are not the works of men, but have come down to us as a result of the inspiration of the Holy Spirit by the will of the Father of the universe through Jesus Christ, what are the methods of interpretation that appear right to us, who keep the rule of the heavenly church of Jesus Christ through the succession from the Apostles.

There are certain mystical revelations made known through the divine Scriptures is believed by all, even by the simplest of those who are adherents of the word; but what these revelations are, fair minded and humble men confess that they do not know. If, for instance, an inquirer were to be in a difficulty, about the intercourse of Lot with his daughters, or the two sisters married to Jacob, or the two handmaids who bore children to him, they can say nothing except that these things are mysteries not understood  by us.

But when the passage about the equipment of the tabernacle is read, believing that things described therein are types, they seek for ideas which they can attach to each detail that is mentioned in connexion with the tabernacle. Now so far as concerns their belief that the tabernacle is a type if something they are not wrong; but in rightly attaching the word of scripture to the particular idea of which the tabernacle is a type, here they sometimes fall into error. And they declare that all narratives that supposed to speak about marriage or begetting children or wars or any other stories whatever that may be accepted among the multitude are types; but when we ask, of what, then sometimes owing to the lack of thorough training, sometimes owing to rashness, and occasionally, even when one is well trained and of sound judgment, owing to man’s exceedingly great difficulty in discovering these things, the interpretation of every detail is not altogether clear.