Fundamental Principles : The Double Threat

You should at all times be on the alert for a chance to put the enemy under the necessity of doing two things at once - and you should try to avoid putting yourself into such a difficult situation. This means that the key to success in chess is A DOUBLE THREAT. A threat to one enemy piece alone is normally parried with ease and is worthless except for some reason ulterior motive. But a double threat is terrific.