Depth is linked to feeling, height to thought and width to activity. So, we should not speak of deep thoughts but of elevated thoughts, nor of elevated feelings but of deep feelings.
As for activity, it must be broad and vast. During its growth, a tree successively develops in three directions.
To begin with, the seed gives birth to the root, which sinks down into the soil. The longer the root and the deeper it goes, the taller and broader the tree will be.
Then the trunk grows and rises to the heights. Once the depth of the roots and the height of the trunk have been established, the tree can spread its branches wide.
Human beings must grow and expand the same way a tree does. It is not until they have deepened their feelings that they can elevate their thoughts, and once their thoughts become elevated, they can then broaden their activity.