One of man's most urgent requirements is food. In contemplating virtually any hypothetical survival situation, the mind immediately turns to thoughts of food. Unless the situation occurs in an arid environment, even water, which is more important to maintaining body functions, will usually follow food in our initial thoughts. The survivor must remember that the three essentials of survival—water, food, and shelter—are prioritized according to the estimate of the actual situation. This estimate must not only be timely but accurate as well. We can live for weeks without food but it may take days or weeks to determine what is safe to eat and to trap animals in the area. Therefore, you need to begin food gathering in the earliest stages of survival as your endurance will decrease daily. Some situations may well dictate that shelter precede both food and water.