The City of God has knowledge of things accessible to understanding and reason, though small because of the corruptible body that weighs down the soul. For, as the Apostle says, "we know in part."
Yet this knowledge is most certain. It also trusts the senses, which the soul uses through the body, when some thing is evident. For the man who supposes that they should never be trusted is deceived in a more wretched manner.
It also believes the sacred Scriptures, old and new, which we call canonical. By them faith itself was nurtured, the faith from which the righteous man lives (Hab 2:4).
Through it we walk without wavering while we are absent from the Lord (2 Cor 5:6). Keeping this faith and being convinced of its truth, we may doubt without just blame concerning certain things.
These are things we cannot grasp either by sense or by reason, which canonical Scripture does not clarify for us, or whose report has not come to us from witnesses whom it would be absurd not to believe.
Indeed, who, while living in this corruptible body that weighs down the soul (cf. Wis 9:15), can comprehend every truth, if the Apostle said that we know in part (1 Cor 13:9)?
Yet this will occur through the Holy Spirit, from Whom we have now received the pledge (cf. 2 Cor 1:22), that we shall attain the very fullness of which the same Apostle spoke.
He said, "Then we shall see face to face," and, "Now I know in part, but then I shall know, even as I am known" (1 Cor 13:12).
For this reason he does not know in this life everything that the Lord promised us for the future, unto perfection, through the love of the Spirit, saying, "He will guide you into all truth," or, "He will lead you to all truth."