“Constant practice devoted to one subject often prevails over both ability and skill.”

Quoted from his first book https://en.wikipedia.org/wiki/Success_and_Failure_Based_on_Reason_and_Reality, "Success and Failure Based on Reason and Reality" https://www.amazon.co.uk/SUCCESS-FAILURE-BASED-REASON-REALITY/dp/9970983903/ on Amazon, P.96 (July 2018)

Book Sometimes you win Sometimes you Learn
Variant: Responsibility is the most important ability that a person can possess.
Source: Developing the Leaders Around You: How to Help Others Reach Their Full Potential

Turquoise Days, Chapter 2 (p. 237)
Short fiction, Diamond Dogs, Turquoise Days (2003)

The Spiral Staircase: My Climb Out of Darkness (2004)
Context: The one and only test of a valid religious idea, doctrinal statement, spiritual experience, or devotional practice was that it must lead directly to practical compassion. If your understanding of the divine made you kinder, more empathetic, and impelled you to express this sympathy in concrete acts of loving-kindness, this was good theology. But if your notion of God made you unkind, belligerent, cruel, or self-righteous, or if it led you to kill in God's name, it was bad theology. Compassion was the litmus test for the prophets of Israel, for the rabbis of the Talmud, for Jesus, for Paul, and for Muhammad, not to mention Confucius, Lao-tsu, the Buddha, or the sages of the Upanishads.

Induction and Analogy in Mathematics (1954)
Context: The efficient use of plausible reasoning is a practical skill and it is learned... by imitation and practice.... what I can offer are only examples for imitation and opportunity for practice.

Source: 1950s, The Skills of the Economist, 1958, p. 15

Source: Genome (1999), Chapter 1 “Life” (p. 12)

Source: "Does the history of psychology have a future?." 1994, p. 475