I've heard people talk about how important their moral compass is to them. What this means can be something different to any different person, but one definition that I think matches most people's conception is, "a natural feeling that makes people know what is right and wrong and how they should behave." Are the natural feelings we have really what should make us know what's right and wrong?
Doing what's natural may not be a terrible basis for morality, but it's not a good one either. We have a number of pack animal and cooperative instincts that guide us toward some caring and concern for our fellow man (and remember man is gender neutral in this context). These also create an aversion toward malice in many contexts, which is also good. Our instincts don't stop with these, 'love your neighbor' drives though.
Being a pack animal leads to a set of instincts, and while some of those are positive like what's stated above others are decidedly negative. It leads to a tribalism, probably due to competition with other packs. We protect our own, but those who aren't are own are usually fair targets for whatever we can dish out. This is why looking at history we only seem to have been fighting against racism, sexism, or similar discrimination for about a century or two, and to some even that's being quite generous. There's also significant drives to personal status and individual gain. We want the pack to be strong, but we also want to be the head of the pack (or at least be very secure about our position in it) and there's a good chance we're willing to trade the good of our group for a high position in it, too. This is why children throw tantrums, politicians and important businessman are as willing to admit mistakes as they are to part with teeth, and people gossip about the shortcomings of acquaintances.
This leads me back to the idea of a moral compass. Truthfully, I think it's a good analogy as long as we remember one thing: a compass doesn't operate in a vacuum. A compass is a magnetized needle set on a spindle (or sometimes in other ways, such as suspended in a liquid). It points to the north because it aligns itself with the Earth's magnetic field. In morality, this leads to the question that might be much more important than how is your moral compass, but what is your moral Earth's magnetic field.
What things external to ourselves help us understand what is moral and what is not? Is it divine scripture? Public opinion and associated feelings of dignity or shame? Articulate and interesting discussions on ethics? All of these have flaws which must be examined and guarded against and all have certain merits as well. Compasses can be disrupted by anything that produces strong magnetic fields, like high electrical current. Precise navigation may also require an adjustment between magnetic north and 'true north' since the Earth's magnetic poles aren't perfectly aligned with her north and south poles. Just like a compass will not point true in a lightning storm or around power lines we should learn where our moral compass may fail to point us true and why if we want to stay true to our moral north wherever we go.
