Scylla/Charybdis

One of Odysseus' challenges were Scylla and Charybdis.Odysseus was caught between a "rock and a hard place". Meaning that he had to make a very hard decision. When someone uses that phrase they are really saying that there is always a choice that one can make, they may just be choices that you do not like. Odysseus had to choose between having his whole ship sink by Charybdis the whirlpool, or have six of his men be eaten by Scylla. He deemed it better to lose six men than to have his entire ship sink.