Union is not a collection of people working together towards a common cause, but the harmonious balance of thoughts, emotions, and body working together as One mind within an individual. Being in union is the conscious attainment of perfected individuality from out of the collective unconscious of humanity. ~Nathan & Aline
In this, our ‘thoughts’ are the father, our ’emotions’ are the mother, and our ‘body’ is the child. This also lines up with the Hermetic flow of reality generation, where Source inspires our Higher Self, which in turn inputs intentions into our thoughts, then our feelings process our thoughts, and finally our body outputs (manifests) everything into actions.
Source → Higher Self → Thoughts → Feelings → Actions
The first Hermetic Principle states that “the All is mental”, and this makes sense when we understand that our thoughts represent our conscious mind, our emotions represent our unconscious mind, and our body represents our subconscious mind. It is our task to allow our higher observer self to program its intentions into our conscious mind, so that we can process them with our feelings, which is our unconscious mind, where they will then ground through our physical body, which is our subconscious mind, to manifest our creations. Union is our three minds working together in harmony as One mind.
Unfortunately, most people have a bunch of subconscious baggage from their genealogical bloodline (nature) that is running half of their show, then they also have a bunch of unconscious beliefs that they gained from societal and familial programming (nurture) running the other half, and thus the conscious mind is merely along for the ride following their lead. In this pattern, the subconscious and unconscious minds tell the conscious mind how to act and feel, and people accept this and walk about as pre-programmed robots, where nature and nurture were their programmers. It is the goal of the alchemist to exercise their strength of will to untangle and transmute their subconscious/unconscious limiting beliefs and patterns, so that all might be intentionally conscious from the higher self down as a ternary being, rather than from the bottom up as a binary one.
For more on the three minds, see the article: The War Against Individuality