Three features predominantly in esoteric symbolism and is the number to which the expression “all” was given, as every other single-digit number is derived from the three.
Religions and other ancient traditions like hermetic mystery schools place great importance on the Trinity or Triad. Some researchers believe the power of the three is why ancient civilisations built pyramids.
The hermetic principle of three is universal in nature and reflects "heaven, earth and water" - or in other words, body, mind and "spirit" (consciousness).
It is the body, mind and soul of humans and our experience of birth, life and death, past, present and future, beginning, middle and end.
When attributed to the life of humans, the three is the final act of the laws of nature which determine what manifests in your life; existing state - dissolution - transformation into a new state.
To give you an example, if you have a pan of water in a fixed state, but then apply heat, the water becomes steam. When the steam cools again it becomes vapour, a return to water.
In humans, the transformation of energy should really be concentrated on the transcendence of consciousness; as the ancient alchemists called it, turning base metal into gold.
This is, of course, is the exoteric view and left alone with little consideration and further exploration means very little. As a matter of fact, it means nothing.
So why is the three revered as such an important number in ancient symbolism? After all, the number three appears in practically every myth, religious text and fairytale. It even shows up in corporate logos quite often. Just saying.
The deeper meaning of the number three essentially describes the process of evolution, which also includes your evolution; the expansion of conscious awareness.
Likewise, the three can refer to the de-evolution of the human psyche. Society is designed to keep your mind rooted in the ignorance of base consciousness. You have a choice; believe the lies of politics, mainstream media, education etc, or create your own story.
There are three sides to every story; one side, the opposing side and the Truth.
Ancient mystery schools say, follow the Middle Pillar.
When reoccurring threes enter your life, it is an indication that a cycle of manifestation has occurred and the results will appear in your life. Watch for number fours and you will get a glimpse of your future.
If the manifestation is not what you desired, approach the goal in a different way, therefore, the three is a sign to express yourself creatively or plan future goals in relation to past experiences.
A positive three assures success whilst a negative three leads to failure. Therefore, if you do not act upon consecutive threes and manifest the powerful energy within them, the things you desire most in life will not manifest.