1. The integral of the gravitational potential taken around any loop trail you choose to hike always comes out positive.

2. Any stone in your boot always migrates against the pressure gradient to exactly the point of most pressure.

3. The weight of your rucksack increases in direct proportion to the amount of food you consume from it. If you run out of food the rucksack weight goes on increasing anyway.

4. The number of stones in your boot is directly proportional to the number of hours you have been on the trail.

5. The difficulty of finding any given trail marker is directly proportional to the importance of the consequences of failing to find it.

6. The size of each of the stones in your boot is directly proportional to the number of hours you have been on the trail.

7. The remaining distance to your chosen campsite remains constant as twilight approaches.

8. The net weight of your boots is proportional to the cube of the number of hours you have been on the trail.

9. When you arrive at your campsite it is full.

10. If you take your boots off you’ll never get them back on again.

11. The local density of mosquitoes is inversely proportional to the amount of your remaining insect repellent.