Rabbi Akiva lived during the time after Judea had been conquered by the Romans. Even though the Roman rulers had made it illegal to study Torah, Rabbi Akiba kept his school open and continued to teach his students.
One day someone said to him "Akiva, why do you break the Roman law by teaching Torah? Do you wish to be imprisoned - or worse?"
Akiva answered him with this story: Once as a fox was walking alongside a river, he saw fish going in swarms from one place to another. He said to them, "What are you fleeing from?" They replied, "From the nets cast for us by human beings." The hungry fox said to them, "Would you like to come up on the dry land so that you and I can live together in the way that my ancestors lived with your ancestors?" They replied, "Are you the one that they call the cleverest of animals? Rather than being clever, you are foolish. If we are afraid in the element in which we live, how much more in the element where we would die!"
Rabbi Akiva then explained: "So it is with us. As fish surely will die without water, so the Jewish people surely will die without the Torah." As water is home to the fish, Torah is home to us.