A hexagram is the combination of two trigrams bound in a relationship with one another. The combination of one of eight entities in combining with another of the eight entities forms one of 64 possible relationships. The relationships -like with any entity includes the one each entity has with itself.
Each trigram can be in relation with another trigram in one of two ways, the dynamic of each reciprocal is unique. Physical world metaphors illustrate the dynamism within each hexagram well. For example:
A Mountain in a Lake
is a very different affair from
a Lake on a Mountain.
Unique patterns emerge when elemental forces, or entities meet in different ways. In each hexagram, a trigram is represented above the other. This up/down gradient translates to influence the dynamic relationship in each combination.
To reiterate, each hexagram is a relationship. It is also a pattern - another way of saying the same thing, as patterns are relationships between -a minimum of - two forces/entities.
I recommend when first encountering the I Ching as an alternative to immersing immediately into the 'occult' or deliciously exotic names of the hexagrams and historical commentaries, instead ponder each hexagram in two ways.
The geographical / geological / seasonal / meteorological / ecological, the 'animated "inanimate" interactions of:
Increasingly (yang)/// Heaven, Water, Thunder, Mountain, Lake, Fire, Wood, Earth ////increasingly (yin)
and
The interpersonal / psychological / familial family dynamics between the the idealized
increasing (Yang) /// Father, Eldest brother, Middle brother, Youngest brother, Youngest sister, Middle brother, Eldest sister, Mother /// increasinly(Yin)
The I Ching is not like subtle accumulative narrative mythos of tarot cards. More than the visceral human drama/comedy, it is the very nature of simplicity and the self evident. The infinite wisdom that we can all see in nature. Each Hexagram is a situation, and understanding the interaction inside a hexagram can lead to a greater understanding of one's own circumstances.