Hebrews 8:5 They (the earthly) serve a copy and shadow of the heavenly things.

The OT, the priest, the sacrifices, the temple, and temple worship were only a copy and a shadow of heavenly things. This complements the fact that the Bible is the unfolding revelation of Christ and the redemption of man. The Bible is the revealing of Christ. 

When we understand this, the Bible opens up to us. We are then able to interpret its deep truths. For instance, previously we were introduced to a mystery person, Melchizedek.  When we believe the OT is a physical picture of NT spiritual truths that reveal Christ, we easily can see how Melchizedek would be an OT picture of Christ. Based on this principle,

Hebrews Chapters 8, 9, and 10 gives us an in-depth teaching on how the OT copies and shadows gives us physical pictures of NT realities. With this in mind, we see the reality of Jesus as the Great High Priest, the minister of the holy places in heaven.