This dark page reminds me of sin. Because you and I are sinners we want to have our own way instead of God's way. Wanting our own way is sin. Doing, or saying, or thinking bad things is sin. Sin is disobeying the rules God has given in His book, the Bible.
Sin causes sadness in our world.
All means every one of us, including you and me. Sin separates you and me from God because He is perfectly right-without any sin at all. God cannot allow sin where He is. God has said sin must be punished. God knew there was nothing you could do to get rid of your sin.