This idea is another step in the direction of identifying cause and effect as it really operates. You see no neutral things because you have no neutral thoughts. It is always the thought that comes first, despite the temptation to believe that it is really the other way around. This is not the way the world thinks, but you must learn that it is the way you think. If it were not so, perception would have no cause, and would itself be the cause of reality. In view of its highly variable nature, this is hardly likely.
In applying today's idea, say to yourself, with eyes open:
"I see no neutral things because I have no neutral thoughts."
Then look about you, resting your glance on each thing that catches your eye long enough to say:
"I do not see a neutral ____ because my thoughts about ____ are not neutral."
For example, you might say:
"I do not see a neutral wall, because my thoughts about walls are not neutral."
"I do not see a neutral body, because my thoughts about bodies are not neutral."
As usual, it is essential to make no distinction between what you believe to be animate or inanimate; pleasant or unpleasant. Regardless of what you may believe, you do not see anything which is really alive and really joyous. That is because you are unaware as yet of any thoughts which are really true and therefore really happy.