Well, the “nature of man” according to John Calvin anyway. Calvin writes:
“In this upright state, man possessed freedom of will, by which, if he chose, he was able to obtain eternal life. It were here unseasonable to introduce the question concerning the secret predestination of God, because we are not considering what might or might not happen, but what the nature of man truly was. Adam, therefore, might have stood if he chose, since it was only by his own will that he fell; but it was because his will was pliable in either directions and he had not received constancy to persevere, that he so easily fell. Still he had a free choice of good and evil; and not only so, but in the mind and will there was the highest rectitude, and all the organic parts were duly framed to obedience, until man corrupted its good properties, and destroyed himself” (John Calvin, Institutes, 1.15.8; underlining mine).
Here are some insidious implications for Calvin’s statement that “man possessed freedom of will, by which, if he chose, he was able to obtain eternal life.”
“… if he chose, [man] was able to” usurp the throne of Christ and crown himself king by meriting eternal life and blessedness for himself and his posterity.
“… if he chose, [man] was able to” to receive power and riches and wisdom and strength and honor and glory and blessing (cf. Revelation 5:12).
“… if he chose, [man] was able to” obtain the SAME GLORY as Jesus Christ and thus profane and cheapen the absolute uniqueness and exclusivity of the redemptive work of Jesus Christ for His people.
Of course, those who believe like Calvin would (probably) say that it is due to God’s “infinite and beneficent condescension” that man even possesses this grand and god-like ability to erase Jesus Christ from history by adorning himself with the glory that belongs SOLELY to Jesus Christ. This is to attribute to creature-man qualities of character that belong to Jesus Christ ALONE. This is to exchange the redemptive glory of God in the face of Jesus Christ for the self-righteous glory of man.