Like any day that changes the world, the Day Our Subway Went on the Automatic Fare Collecting System will be remembered differently by different people. Every person who was lucky enough to be a participant will have his individual story, except that all of the anecdotes begin with," You know what happened when I put a $5 bill in that thing?"

But there was one ominious incident that was set apart from the human saga that took place on underground stages all over the city. It was reported, amid the front-line dispatches from the Fare Card machines, that one card-holder got hom, only to have her card's magnetic properties erased by the magnetic device that opens her garage door.

Do you know what this is? This is a declaration of war against the Metro by the Automobile. If we are to be allowed to speed merrily about, whenever we want (except nights and weekends), wherever we want (as long as it's on the Red Line or the Blue Line), we had better be prepared to defend the Metro.

Unfortunately, it is being attacked in its weakest point, the one that doesn't work. Whoever thinks that there will ever be a machine that will take money, issue a product and make correct change, has never kicked a candy bar under glass or watched his coffee being sprayed on the coffee lounge floor.

However, we've got these machines, and we don't want San Franciscans to think that we can't do anything they claim to. Unless we want to be forced back into out cars - and that garage incident reveals their true nature - we will have to learn to live with them.

Passengers can help by always carrying fresh money. The amount of dog-earred currency people try to palm off on machines is disgraceful. If you have attractive, as well as exact, amounts, the machine may be tempted to take it. But if it does not one shoul if it does not, one should try to retain some perspective. Win a few, lose a few is a good attitude with which to stand in line.

The Metro management can also be helpful, and, indeed, so far it has been. If they continue to have a corrective apparatus on location, the automatic system will work just fine. For every machine, all you need is one human being to stand by, give out change, refund lost money and issue farecards.