Generally speaking, people who are at lower levels of an organization serve those at higher levels. Bosses boss and their employees serve; coaches devise strategy and players do what the coach tells them to do; engineers design car parts and workers assemble them according to the engineers' instructions. Ideally, of course, it's a two-way street: A good boss knows he is really there to help his employees succeed; a good coach creates strategies based on his players' strengths. Even there, though, the boss and coach are really working in service of a higher goal, seeking organizational success. The same is true in the spiritual sense of the Bible. When someone serves another, they are in a lower state, serving a higher state (or a deeper evil, if they are being enslaved by people who represent evil). This can take many different forms, depending on the circumstances. In many cases, this creates a connection between "service" and intellectual things. This is because who we are is determined by what we love; our loves are the deepest part of us. What we think, our reasoning and intellect and the things we learn about, come from those loves and serve those loves.
Zechariah 12:10-14
10
I will pour on the house of David, and on the inhabitants of Jerusalem, the spirit of grace and of supplication; and they will look to me whom they have pierced; and they shall mourn for him, as one mourns for his only son, and will grieve bitterly for him, as one grieves for his firstborn.
11
In that day there will be a great mourning in Jerusalem, like the mourning of Hadadrimmon in the valley of Megiddon.
12
The land will mourn, every family apart; the family of the house of David apart, and their wives apart; the family of the house of Nathan apart, and their wives apart;
13
the family of the house of Levi apart, and their wives apart; the family of the Shimeites apart, and their wives apart;
14
all the families who remain, every family apart, and their wives apart.
