In music there is an idea of tension and release (typically a dominant V chord resolving to I) – everything from classical to jazz music is constructed upon the interplay of tension and release.
So it is in life and astrology – nothing interesting happens without tension. Just as the musical tension motivates its resolution, a tension in life in the form of lack, frustration or challenges motivates its resolution.
This thought permeates astrology, especially when we think of aspects. Think about aspects in terms of Lunation Cycle for example (taking the major aspects only for sake of simplicity):
Conjunction – the New Moon – is the ending of old cycle, and beginning of the new cycle. There is a temporary inertia that is neither tension nor release (or maybe it’s both) – it’s ground zero. The New Moon birth may have to battle this inertia within themselves, to push themselves into action – most likely through the help of another person. The meeting of Sun and Moon implies fecundation – hence the importance of a relationship.
Sextile is the resting point from the initial action of New Moon – there is a temporary release of tension. Which will soon give rise to another tension in…
Square – the Half Moon – is the creation of tension, a new direction or challenge that calls for its resolution in…
Trine – a major point of stability and release. The ideas and themes originated in Conjunction and Square seem to find satisfactory conclusion – one feels the flow of well established identity/skills/roles that was initiated in the previous phases.
Opposition – the Full Moon – This is the culmination and turning point of the New Moon theme originated in the conjunction. There is full awareness of the completion of the New Moon theme, and then the necessity for new challenge emerges, which finds release in the 2nd Trine, etc, etc…
If the horoscope lacks tension (hard aspects), there is a major need to create one through taking on tough challenges – or there will be a lot of misdirected emotions trying to stir up energy. If the horoscope lacks ease (flowing aspects) – there is a need to find a place of rest, of introversion.
So if you have tension in some part of the horoscope (through square or opposition), know that they are calling out for release. If you have ease (or release) in other parts of the chart, know that they are calling for new challenge, either based on the strength that is already present, or through an entirely new endeavor (bringing the planetary combination to a new level of expression).