A tree that develops many branches without developing roots must be pruned in order to preserve a proper ratio between them.
Since a person has no gardener to prune him, he has no choice but to develop roots.
When he reaches a certain level, when he has sprouted many branches, he must make sure that this growth is matched in his roots – in his actions in the world of action.
If he neglects his roots, he will lose his stability and balance, and will likely be uprooted.
–Rabbi Adin Steinsaltz