There can be no impact without being fluent in the unknown, no fluency in the unknown without impact.
That's what it is in short. Though the opposite aspect is about conflicts, it's funny that the conflicts on this forum seem to be somewhat on the decline during this aspect. I might be wrong in that observation, but just how it feels to me. More spesifically, that when you dont feed the sceptics with your theories of the unknown, they lose their arguing juice, and when you dont feed believers with the sceptical views then the believers will pacify. As the energy of Mars diminishes when Neptune lags behind. Mars = offensiveness and assertion, self-defense (which is more than often offensive in nature), and Neptune = the unkown, the sense of great things beyond your scope, a fleeting but grand sense. Opposition aspect, the energy production of those two is increased as long as neither lags much behind. If one lags behind, the other may become less strong, facing a great hindrance in it's energy production. Basic astrology math when you put them together.
One supposed-to-be law of opposites is that only one may be properly active at a time and the other must stay behind while so. Approximately. But it is rumored & hypothesised by at least one more prominent astrologer that when two separate ends of the opposite unite, it becomes a greater state of enlightment. Seeing both sides of the coin in one picture. I have a feeling this creates an energizing feeling for those coming to this state.
A both enlightened and positive state of this could be to feel vital and full of life when you get into the vastness of the unknown with either great, dancer-like fluency, or without holding back, or both... it's so hard to put proper words to Neptune. It's simply vast, rolls fast and shifts, and is out there, just like it is in the space for us. It's quite a direct metaphora of it's physical form, as everything in astrology seems to be.