GEN.2:16-17  And the LORD God commanded the man, saying, Of every tree of the garden thou mayest freely eat:  17But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die. What is this tree that can bring death to man?  Now we know that death comes because of sin RO.5:12  Wherefore, as by one man sin entered into the world, and death by sin.  Therefore we can see that it is sin that brings death to man , but what brings us the knowledge of what sin is? The law.  RO.3:20   Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.  Therefore the tree of knowledge of good and evil is the law for by eating of the tree death entered into the world.  Now is the knowledge of good and evil ( the law ) sin RO.7:7  What shall we say then? Is the law sin? God forbid. Nay, I had not known sin, but by the law: for I had not known lust, except the law had said, Thou shalt not covet.  So then if the eating of the law was not sin what was?  Was it not in the breaking of the commandment THOU SHALT NOT, the fruit itself was not the sin , for after God created all the trees He saw that it was good.Gen.1:12  So then why did God command man not to eat of the tree of knowledge of good and evil if there was nothing sinful in the fruit. Is it not because God placed a covering over man in the commandment THOU SHALT NOT , so that man would not see his sinful nature (remember man was created outside of the garden ) because when man sees himself though the eyes of a righteous God his sins overwhelm him and he runs and hides from God , just as Adam hid himself when his eyes became open. Where else do we find the phase THOU SHALT NOT is it not in the commandments that God set down for all men. (Ten commandments ) Therefore the phase THOU SHALT NOT is a commandment of covering , if we listen to it we do not eat of our sinful nature, but we have a foreshadowing of the covering that Jesus Christ gives us. Therefore it was not the eating of the tree of knowledge of good and evil that was mans sin but the breaking of the commandment THOU SHALT NOT.