A roller can't move everywhere it wants to. Neither can water, fire, or anything else that's just natural or natural with senses but no reason. Many things can block what they're trying to do. But the mind has a special power. It can move through any obstacle according to its own nature. It can keep going straight ahead.
Think about this amazing ability of your mind. It can pass through anything. It can move in all directions — up like fire, down like a stone, or sideways like a roller on a slope. Be satisfied with this power. Don't look for anything else.
All other obstacles that seem to block you aren't really blocking your mind. They either affect only your body, or they come from wrong opinions. Your reason isn't fighting back like it should. Instead, it's giving up weakly and letting itself be beaten.
Unto the _cylindrus_, or roller, it is not granted to move everywhere according to its own proper motion, as neither unto the water, nor unto the fire, nor unto any other thing, that either is merely natural, or natural and sensitive; but not rational for many things there be that can hinder their operations. But of the mind and understanding this is the proper privilege, that according to its own nature, and as it will itself, it can pass through every obstacle that it finds, and keep straight on forwards. Setting therefore before thine eyes this happiness and felicity of thy mind, whereby it is able to pass through all things, and is capable of all motions, whether as the fire, upwards; or as the stone downwards, or as the _cylindrus_ through that which is sloping: content thyself with it, and seek not after any other thing. For all other kind of hindrances that are not hindrances of thy mind either they are proper to the body, or merely proceed from the opinion, reason not making that resistance that it should, but basely, and cowardly suffering itself to be foiled;