Now faith is the substance [assurance] of things hoped for, the conviction of things not seen. For by it the people of old received their commendation. By faith we understand that the universe was created by the word of God, so that what is seen was not made out of things that are visible.
And without faith it is impossible to please him, for whoever would draw near to God must believe that he exists and that he rewards those who seek him.

This portion of Scripture shows the power of faith and what it realises (gives substance to), in relation to what we hope for; in essence it demonstrates to our soul what we cannot see, but will see in the future (JND). The 'substance' or better 'assurance' is from the Greek: hypóstasis meaning "to stand under", thus is to properly to possess or have a ligitimate claim to an object or action. Jamieson, Fausset and Brown Commentary suggests if we look back to Hebrews 3:14 we note it is with confidence we participate in Christ - and the confidence we had at the beginning needs to endure to the end: "For we have become partakers of Christ if we hold the beginning of our confidence steadfast to the end." So also our faith. Sure faith infers the reality of the objects believed in and hoped for. To the believer the thought is clear and simple; it assues the mind.