Compassion
Everywhere I go I meet people of vast wisdom. I have heard it from such angels that compassion should not be developed without wisdom alongside it. They also say that enlightenment can be attained by either of two possible paths: the path of the intellect, or the path of compassion. Not surprisingly, the path of compassion is by far the more popular of the two - it does not involve having to think. Yes, wisdom is developed "alongside" compassion alright - but so far to the side that it is not even remotely visible.
They (and who are not "they") avoid thinking at all costs, content with the pleasure they milk from their small and skillful compassion. In their deepest of thoughts they think "What need have we of reason? It is superfluous!" They sincerely believe wisdom to be merely a skillful way of performing their commonplace compassion. Their "wisdom" is merely something to prop-up the frail feelers of their cowardly compassion.
The compassion and wisdom of the truly wise are two aspects of the same thing, the Infinite. Clearly it is impossible to have such compassion without wisdom; theus any talk of having wisdom "alongside" is mistaken. If one does not understand one's own nature, and the nature of Reality, then how can one hope to do any good at all? No matter how many virtues you may have cultivated, for all your vast compassion and mercy, your every action will be in vain.
It is the One thing that must be developed, and this One can only be found through a transcendent use of the intellect. So keep life simple, save yourself a lot of unnecessary mental effort, and restrict yourself to one virtue only. Heed my advice: cultivate the wisdom of the Infinite and you will gain All. Compassion, mercy, and the countless other virtues will no longer be a concern to you. No longer will you be bothered with examining your personal motives, as you will no longer exist in the world of motives.