Who said, "Rough seas make good sailors"?

As mentioned above, this quote has many sources and it is
more about what it means or implies that is important rather than its origin as a direct
quotation. The saying evidently has its beginnings in one or more proverbs and is
considered to be something of a cliche (an overused saying). The link between the
proverbial sailor who survives a "rough" sea and the average person who must rise to
certain life challenges and emerge a better person is apparent. A sailor who survives a
rough sea has a perspective he would not have had
previously. 

Everyone can relate to the sea and to stormy
weather and relationships are often compared to rough seas. Therefore, a visual picture
is easily created which makes this a good means of relaying a message. A storm is a
naturally-occurring event and a sailor uses his knowledge to navigate a storm. Each
storm that the sailor successfully steers his ship through makes him a better, more
experienced sailor. He will be better equipped for the next one and will have more
understanding of his opponent- the sea. If he never has any challenges, the possibility
exists that, when he is caught in a storm of seemingly massive proportions, the sailor
will be unable to cope and the ship will be destroyed and the sailor (and potentially
many others) will die: so too in life. For some, there are many life challenges and when
an all-consuming event occurs, they are able to put it in perspective, manage it and
move on with life, despite the associated trauma. However, others, when they are faced
with an enormous challenge, cannot cope and their relationships fail or their physical
or even mental health suffers. In other words, challenges are a necessary part of life;
they are character-building and give depth to a situation, allowing a person to see the
point of view of another person just as a rough sea is crucial to the development of a
good sailor. As Atticus Finch says in To Kill A Mockingbird,
challenges allow a person to "climb into another man's skin and walk around in it"
(chapter 3).