"beware of trojan horses" is a common piece of advice. explain the historical context of this phrase.

Trojan Horse comes from the story where the Greeks uses trickery to enter Troy during the trojan war.  This tale demonstrates the tricks that can be used to win a battle or launch an attacked.  The term is used in computer security and much more.  The lessons learned from this tale is a general lesson we can take from history into every aspect of life where one has to protect something that can be violated by others using subterfuge.