The motif of brotherhood
Monks are "brothers" by oath, especially during this time of Christian history, but also in almost every other kind of monastery. This motif shows that although the intention of meditation, scripture, and discipline is individual union with creation and God, humans literally cannot function alone. In order to lend sustainability and stability to the monastic intentions of each individual, they must become like brothers, working through conflict and relationship.
The motif of relationship
There are other kinds of union that these rules imply. They imply that all the monks are earnestly striving to understand new truths about themselves, which is union to self. The rules also presume at attempt at uniting with God, and many rule pertain to the protection of that pursuit. Also, there is relationship amongst brothers, and importantly, union with nature by removing the community from the domain of regular society.
The psalms as a symbol
The priority of the Psalms has symbolic importance, because of what the Psalms represent in the Bible. To prioritize the Psalms for daily recitation is to prioritize human literature and poetry as an essential component of religion. The Psalms are poetry about personal agony, paranoia, addiction, confusion, betrayal, remorse—it is deeply human, and the Psalms are surprising candid, so their priority of the Psalms represents a desire to find the "plain, poetic truth."
The meaning of injury
To see what injury represents in the human experience is to ask the problem of pain: How could God invent a world that is the platform for so much brokenness, strife, accident, and even malice—how could he design a world for us like this and still love us? Their symbolic journey to understand violence and non-violence is demonstrated throughout the rules, but especially in the rules about injury.
The last rule
The last rule is to abandon the rules when they're done being helpful. This list of rules is specifically designed to be used, exhausted, and then tossed in the trash, so to speak. The last rule is perhaps the most important of all for the transcendentally-oriented folks: Without trusting one's self to be the avatar for divine consciousness, there are tragic limitations in one's pursuit of God. Therefore, the last rule symbolizes the only true rule, which is to constantly learn, but to trust one's self and one's instincts as evidence of divinity.