“Morality, if present, should not be relied on because it will be trumped by self interest in most circumstances.”

Variant translation: When all your judgements are based on your own wisdom, you tend towards selfishness and fail by straying from the right path. Your own judgements are narrow minded and have no persuasive power or growth for others. It is best to consult a wise man when a fit decision does not occur to you. A wise man is a fair judge from an objective point of view. He is passing judgement for the benefit of others, not for his own sake. A judgement passed using only one's own wisdom is just like thrusting a stick into the ground and expecting it to grow!
Hagakure (c. 1716)
Context: It is difficult for a fool's habits to change to selflessness.... Because we do most things relying only on our own sagacity we become self-interested, turn our backs on reason, and things do not turn out well. As seen by other people this is sordid, weak, narrow and inefficient. When one is not capable of true intelligence, it is good to consult with someone of good sense. An advisor will fulfill the Way when he makes a decision by selfless and frank intelligence because he is not personally involved. This way of doing things will certainly be seen by others as being strongly rooted. It is, for example, like a large tree with many roots. One man's intelligence is like a tree that has been simply stuck in the ground.
We learn about the sayings and deeds of the men of old in order to entrust ourselves to their wisdom and prevent selfishness. When we throw off our own bias, follow the sayings of the ancients, and confer with other people, matters should go well and without mishap.

Speech at Springfield, Illinois (26 June 1857)
1850s, Speech on the Dred Scott Decision (1857)

Source: The Production of Security (1849), p. 51

The Human: Green Humanism (p. 17)
Straw Dogs: Thoughts on Humans and Other Animals (2002)

1930s, Second inaugural address (1937)

Wikinews interviews three figures from Donald Trump's political past (October 2015)

Source: Emotional amoral egoism (2008), p.15

"The Persistence of Vision", The Magazine of Fantasy & Science Fiction (March 1978), reprinted as the title story in The Persistence of Vision (1978)