The land of Canaan is similar to the Garden of Eden. In order to enter Canaan's blessings today, the promises of God's Word, we must learn Wisdom. And the treasures of wisdom are found only in Christ since the truth of Christ's death teaches us that faith in it is our only way into those promises. Wisdom was placed upon Joshua enabling him to understand how to enter Canaan. Wisdom sees into what God's will for our lives is today.
Wisdom crosses the Jordan barrier - the veil.
That will see us discover all God's Wisdom He has for us. We will learn all biblical teachings and mysteries when we see that in Christ, in reliance upon His work on the cross, these treasures exist. After all, all truths in the Word point to Christ. We will understand that which points towards Christ - the whole of God's Word. Without being in Christ, a person will not understand how to grow righteous in activity and behaviour, and thus be unable to achieve spiritual maturity.