The potion made you very small.  In fact, you  could now fit through the very small door behind the curtain... if only you hadn't shut the door and put the key back on the table!  You are too small to reach over the table.  You are also too small to reach the cake.  You might as well give in and have a good cry.

 (Sob)

 

Principle 3 states that the participant should have natural interactions rather than artificial. For example, a "click here to resize yourself" button would be an artificial placement into the story (It would not be part of the natural events of the unfolding story).  Here, Alice performed a very natural task, drinking from a bottle.  This keeps you as an immersed participant in the story plot.