Serve
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.
Arcana Coelestia # 7009
7009. 'And it will happen, that he will be for you as a mouth' means the truth contained in doctrinal teachings, which also goes forth from the Lord in an indirect way. This is clear from the representation of Aaron, who 'will be for Moses as a mouth', as doctrinal teachings, dealt with in 6998; and from the meaning of 'being for Moses as a mouth' as the utterance or declaration of it, dealt with in 6987. The reason why the words of explanation are 'the truth contained in doctrinal teachings, which also goes forth from the Lord in an indirect way' is that the truth contained in doctrinal teachings, which 'Aaron' represents, is the kind of truth that can be heard and discerned by angels and by men. Such truth is what goes forth in an indirect way from the Lord. But the kind of truth that is represented by 'Moses' goes forth directly from the Lord, and cannot be heard or discerned by men, nor even by angels, see 6982, 6985, 6996, 7004.