Ablaze, the idea then is that if you always have inner joy then external joy will follow? Is that about "As above so below"?
Does Buddhism then teaches the same taoist concept that don't be sad today because you lost what made you happy, because you may be happy again tomorrow? I mean, due to the cyclical nature of all, if today it's yin, tomorrow may be yang?
When joy is derived from external sources, thus dependent on externalities, then it inevitably ends when those external conditions are gone. In other words, if one's sense of happiness and fulfillment is dependent on sense experience, it will have a clear beginning and end. When joy is dependent on the sun shining, then dissatisfaction will arise when it rains.
If we depend on a delicious meal for happiness, then once it's gone, we'll be left craving for more. What we don't have becomes a source of dissatisfaction. Even more so if we take a bite of something disgusting. We become attached to the pleasant and averse to the unpleasant.
If we depend on harmonious music for happiness, then once it's gone, we'll be left craving for more. What we don't have becomes a source of dissatisfaction. Even more so when the neighbors are making excessive noise in the middle of the night. We become attached to the pleasant and averse to the unpleasant.
If we depend on taking a walk through a beautiful garden or well-kept city park for happiness, then once it's gone, we'll be left craving for more. What we don't have becomes a source of dissatisfaction. Even more so when the land becomes polluted. We become attached to the pleasant and averse to the unpleasant.
There is nothing wrong with the positive end of these experiences. It's perfectly alright in Buddhism to appreciate a well-cooked meal, enjoy nice music, and delight in the natural world. It's absolutely natural to not enjoy unpleasant experiences. Our desire-based relationship to these experiences, however, is where unhealthy habits and expectations may manifest.
When we cling and grasp to external conditions, our joy becomes dependent and incomplete. We become addicted, always seeking the next best thing, attempting to control the outer world in order to make it conform to our liking. When we let go of this attachment, our joy becomes independent and unconditioned.
Inner joy is like a reservoir that can never be depleted, independent of conditions, always there whether rain or shine.