An oyster may contain a pearl, and a pearl has great value. I am seeking my fortune in the great wide world, which is thus my oyster, for it may give me a pearl.
The phrase is often used as an inspirational tool to stress that people have choices — that the world is theirs — that they can do what they want with their lives.
In any given oyster, there is a chance — but no guarantee — that a pearl lies within. So it is with life. The world is yours for the taking, whatever you make of it.
The proverb first appears in Shakespeare’s play ‘The Merry Wives of Windsor.’ Falstaff says, ‘I will not lend thee a penny.’ Pistol replies, ‘Why, then, the world’s mine oyster, Which I with sword will open.’
If Falstaff had lent Pistol the money, then Pistol would not have needed to seek his fortune (pearl) by going out into the world (the oyster) and using what he already had (his sword and his skills). His sword would be his means of making his fortune — just as it would be used to pry apart the shell of an oyster.
The oyster is also a metaphor for life. The world holds the possibility of making a fortune, just as one’s life offers the possibility of happiness, but a lot of work may be necessary, as well as trying a lot of different things (prying open a lot of oysters) before one finally makes one’s fortune (finds a pearl).
Violence is not necessarily a part of it. The sword, after all, is nothing but a large knife, a tool used mainly as a weapon. It can also be used in peaceful ways.
Every oyster one picks up may hold a pearl, but most don’t. Finding a pearl requires either opening a lot of oysters or having good luck — either will work. And if there’s no pearl in an oyster, you can survive by eating the meat!