2 Peter 1:9

But he that lacketh these things is blind, and cannot see far off More accurately, For he to whom these things are not present is blind, near-sighted. The causal conjunction is important in the sequence of thought. We are to press on from height to height of Christian excellence, for, if we do not so press, we sink back into a want of power to perceive even the elementary truths of the kingdom of God. The second of the two words describing this state is defined by Aristotle (Probl. 31) as denoting the state of those who are naturally "short-sighted," and is thus adequately rendered in the English version. The man in this state in his spiritual power of vision sees the near things, the circumstances, allurements, provocations of his daily life, but he has lost the power to look to the far-off things of the life eternal. This seems, on the whole, a truer interpretation than that which, taking the definition of the word given by some Greek lexicographers as meaning "one who closes his eyes," sees in it a description of one whose blindness is self-caused, who wilfully closes the eyes of the spirit that he may not look upon the truth. The state of the blind man who saw "men, as trees, walking" (Mark 8:24) offers a suggestive parallel.

and hath forgotten that he was purged from his old sins Literally, and hath taken to himself forgetfulness (the noun is not found elsewhere in the New Testament) of the purification of his sins of long ago. The spiritual fact described is like that of which St James speaks, and indicates a like train of thought (James 1:23-24). The "purification" is that of conversion symbolized and made effectual by baptism, and connects itself with the stress laid upon it in the words that belong to one great crisis of the Apostle's life (Acts 10:15; Acts 11:9; Acts 15:9). The man who forgets this cleansing of his soul, and acts as if he were in his simply natural state, with no power to resist temptation, does in fact ignore what God has done for him, and treats "the sins of long ago" as though they were still the inevitable accompaniments of the present.