Нужно кратко в 4 предложениях объяснить фразу: " man cannot discover new oceans unless he has the courage to lose sight of the shore"

To my mind,this quote means that you have to risk to achieve something.And if you don't have enough courage to risk,you won't probably succeed.Before setting some goals,you have to make sure that you're ready to face many problems and overcome them.So,you must be very brave to discover something new and achieve your aims.