Late in Russell's essay, he writes about the value in seeing children as ends in themselves versus seeing them as potential adults.
If you have the sort of liking for children that many people have for horses or dogs, they will be apt to respond to your suggestions, and to accept prohibitions, perhaps with some good-humoured grumbling, but without resentment. It is no use to have the sort of liking that consists in regarding them as a field for valuable social endeavour, or what amounts to the same thingÑas [sic.] an outlet for power-impulses.
In other words, Russell suggests that the successful teacher enjoys children as children, rather than children as potential adults, and enjoys "being with" rather than "molding" children.
I disagree with Russell here. While teachers would lose their sanity if they did not in any way enjoy the presence of students, if this were their primary joy, my fear is that they would not get around to teaching much. As the whole rationale for teaching is to impart information to students, and the whole rationale for doing that is to make them better off then they were before, teaching requires that one not only enjoy being in the presence of students, but that one stay focused on the goal of shaping students.
To put it a bit more directly, teaching requires that one see students as potential adults and see themselves as instruments to bring students closer to that goal. While Russell's above quote suggests that it "does little good" to regard children as "field for valuable social endeavor," I am hard pressed to see what the rationale for teaching would be if one did not.
Russell goes on to say that, "[t]he desirable sort of interest is that which consists in spontaneous pleasure in the presence of children, without any ulterior purpose."
At the risk of sounding crass, I can only read the words "ulterior purpose" as a synonym for "teaching." At the risk of sounding more crass, if a person solely takes joy in "spontaneous pleasure in the presence of children," then one is best to be a counselor or buddy, rather than a teacher. That is because teaching cannot take place - and would be superfluous - if the teacher did not believe that they could impart something onto the child that the child should have - in other words, seeing the necessity to steer the child in a certain direction they might not naturally go toward.
I have of en thought privately about how many teachers - particularly those in early-years education - seem to love kids more than to love teaching kids. There is a big difference, one that I think Russell overlooks. Loving kids is simply to enjoy being in their company. Loving to teach kids is to enjoy equipping students - sometimes it will be against their will - with tools that (at least the teacher thinks) they need. Contra Russell, good teaching means not just enjoying students, but enjoying the ability to help mold them into something greater than they are now. This means, to some degree, viewing students as an incomplete means, and not as a complete end.
To tie this to my personal experience as a teacher, the teachers I know (myself included) to like being around students (to a degree). What we enjoy infinitely more than this, though, is the feeling that a child learned something from us and the experience of school, for which we know they will be better off. If we simply enjoyed kids, we'd work in day care or volunteer for Big Brother/Big Sister. Teaching is more than this: it is the willingness to see students as potentialities that we can play a part in actualizing.