Saturday is a special day is a well known part of a line from a children's primary song. But why is Saturday such a special day? The song states that it's because Saturday is the day we clean the house, shop at the store, wash our clothes, and shine our shoes so we won't have to work until Monday.
As a kid I always felt like this song was used as a joke or an excuse to get me to do chores. But as I've gotten older I've realized the importance and truthfulness behind this song. Section 108 of the Doctrine and Covenants states: Organize yourselves; prepare every needful thing, and establish a house, even a house of prayer, a house of fasting, a house of faith, a house of learning, a house of glory, a house of order, a house of God. In order for this to happen we need to prepare ourselves both physically and spiritually for Sunday.
Physically we can prepare ourselves by getting our house cleaning, yard work, and shopping done. This ensures that we don't have to do these things on the Sabbath. When we do this the stresses of a messy house or buying food for the next week are gone and our Sunday can be fully dedicated to the Lord.
I know a farmer who told me that he doesn't work on his farm on Sunday. This means Saturday is his busiest work day. He said he knows the Lord blesses him for not working on Sunday by making Saturday a more productive day than the other previous five days of the week combined. This farmer, with help from the Lord, truly makes Saturday a special day.
Along with physical preparation we need to spiritually prepare ourselves. If our actions are not in harmony with the Lord's teachings on Saturday night how is that going to help us prepare for Sunday? Especially when worthiness to bless and partake of the sacrament is so important. I know many young men who've told me they won't participate in the partying, drinking, and immoral activities of Saturday night because they know the next day they have a priesthood duty to be worthy to bless, pass, and partake of the sacrament. They look at it as a blessing in their lives because it's kept them on the straight and narrow path.
So why is Saturday such a special day? Because it's our "get our work done day" so we can be ready for Sunday.