Psalm 105:4 Seek the Lord and His strength; Seek His face evermore!
In the days when the Israelites carried the Ark of the Covenant, they relied on God and His strength which was demonstrated whenever the ark was with them.
The people learned to trust in God totally as long as the Ark was with them; we still seek physical comforts.
God wants us to rely on Him even when we cannot see a physical object we can relate to. Faith is believing in the unseen.
God will still show us signs so we can believe, but our faith is strengthened by believing in the unseen because that is when we see His real power!