People like to make choices for themselves that will lead to gaining what they want in life. When people don't make wise choices, the law steps in to force them to be responsible for them. On the other hand, sometimes we don't have control over the consequences of our choices and chance and/or coincidence may get in the way of the desired outcome of choices. Three people who became subject to chance, and/or other people's choices, are Portia, Antonio, and Shylock in Shakespeare's The Merchant of Venice.
First, Portia cannot choose her husband because her father left it in his will that the one who marries her will be the one who chooses the "correct" box with her picture in it. Portia does her best to help the one she wants to choose the correct box, but before that, she had two close calls as other suitors tried their chances, or luck, with the boxes as well. Portia had no control over her father's will and was forced by the law to obey it.
Then, Antonio tries his luck on Bassanio by lending him credit that, by chance and unfortunate natural disasters, doesn't come back around to be paid. Antonio is then forced to throw himself at the mercy of others and Shylock for his life. Had Antonio not risked so much for a friend, he would not have been forced into the position of having to go to court to save his life.
Finally, Shylock takes his chances by throwing all he had behind the strength of the law. By believing that the law was on his side, he chose not to show mercy towards Antonio. By not showing mercy to Antonio, he was not shown mercy when the tables were turned on him. Shylock loses after making strict choices and betting on the law to help him. He eventually loses everything in the process:
"Nay, take my life and all; pardon not that:
You take my house when you do take the prop
That doth sustain my house; you take my life,
When you do take the means whereby I live" (IV.i.386-389).
Thus, when a person makes a choice, or must rely on luck or the decisions of others, then the consequences aren't usually foreseeable and heartache can be the result.