This was something the Masters told me during the first year they spoke to me. It sounds profound yet simple but, to be honest, I wasn't entirely sure what they meant at the time. In the context of my life then I understood them to be telling me that I should learn to be unmoved by the vicissitudes of emotion and stay grounded but I suspected there might be more because the Masters' words were often capable of interpretation on several levels. For example, a tree has a strong trunk with green leaves at the tips so it is both solid and delicate, firm and still at the centre but responsive and moving at its edges, a good example for the spiritual aspirant who must be centred in the unmoved Mover but able to respond to those around him. A tree gives (fruit, flowers, wood, oxygen) while seeming to ask little for itself. It stands tall but does not bend. It remains unbowed in the most difficult of circumstances. Its roots go deep down into the soil, the underground even, while its branches extend to the heavens. In fact, it could be said to unite heaven and earth which is just what many mythologies have said it does do as the axis mundi. Then we have the Tree of Life, the Tree of Knowledge of Good and Evil, the Tree under which the Buddha gained enlightenment, even the Tree on which Christ was crucified. The whole of manifestation is sometimes seen as a tree. It is the most profound of symbols.
But setting aside all that, I would like to consider the tree in a different aspect here, as a pattern for spiritual development. It is this aspect that I believe the Masters were referring to. One can certainly take the injunction in that respect.
So, how does the tree work in this way? To begin with, it is not the Tower of Babel. There are many schools of esoteric and mystical practice, in East and West, that try to reach God by building a tower to heaven. These have evolved a whole host of methods and techniques in the attempt to do this. It could be a form of yoga or mantras or particular meditations or work on the body or an elaborate metaphysical system or even, and most crudely, drugs and sex. These all have their effects on consciousness but they do not bring true spiritual awareness and they do not do so because they are attempts to take heaven by force. In effect, to steal from God. They are man trying to gain the fruits of the spiritual on his own terms rather than God's, and they will all eventually suffer the fate of the Tower of Babel, if not in this life then later.
The path to true spiritual understanding and being is through growing not building. It should be a natural process that comes from within rather than being imposed from without and, in this context, all that comes from the mind is deemed the without because the thinking mind is external to spirit. That does not mean that growth cannot be encouraged. It should be, but it should not be forced for then it will be artificial and therefore false.
Be like a tree means approach the spiritual path in an entirely natural way, always aspiring upwards but letting growth come from within and not trying to induce it by mechanical means. For one thing, this ensures that the motive is right, that it comes from love of God and not egotistic desire that seeks to gain the rewards of spirituality, power, consciousness, whatever, without being worthy of them. There are certain techniques that have been developed that may well bring results of a sort but, as Valentin Tomberg points out in his letter on the Tarot card the Tower of Destruction, those who build a tower in the attempt to gain heaven will eventually find it struck by a thunderbolt. This means that they will sooner or later be brought back down to earth. The results of their seeking the spirit by building rather than growing will not last. The path to God cannot be built by man and, when all is said and done, true spirituality only comes through grace.
Grace is a concept that is much lacking in a lot of contemporary spirituality because a lot of contemporary spirituality dispenses with God who is the source of grace. But the entrance to Heaven is only gained by means of grace, and grace is only given to those who grow like trees not to those who build towers.