The sea serpent in the next drawing looks like a huge monster because it rises from the water just below the horizon line, so very far away. Instead of the sea, it could also be an endless sandy plain or a vast meadow.
Exercise 1: Draw a horizon line and a figure looking out over the sea or land. Make up another monster in the distance.
Look at the last drawing. It is an example of how all kinds of objects often hide our viewing horizon (the red line).