For his unique creativity and selflessness, he was always attended by Louis XIV and eventually became a trusted advisor to the monarch. He made important contributions to him during his years of service of which the construction of the Versailles palace was the most important.
The passage describes a person who was highly valued by Louis XIV due to their creative talents and dedication.  He played a key role in the construction of the Palace of Versailles, which is considered one of the most significant architectural achievements of the era.