Just that text alone doesn't indicate the.Holy Spirit is the cause. Understanding is also a natural virtue of the intellect.
That's right, it does not indicate. However, given that Leonardo had no formal schooling both options are possible. (Whatever the media writes about him, he died as a confessed Catholic. Unfortunately, I lost the source of that fact - that was years ago). Google AI says this:
"There isn't a "long confession" of Leonardo da Vinci on his deathbed, but historical accounts suggest he expressed regret over not fully realizing his potential, famously stating, "I have offended God and mankind because my work did not reach the quality it should have". This sentiment is documented by Giorgio Vasari, who noted Leonardo's anguish over his life's work not being more focused or fully organized. While a detailed, lengthy confession is not recorded, the belief that he lamented his unfulfilled potential is a recurring theme in historical accounts of his final days in France in 1519.'