Why did Friedrich Schiller consider Goethe a naive poet?

Friedrich Schiller explored the distinction between two types of poetic creativity in his essay Über naive und sentimentalische Dichtung (On Naive and Sentimental Poetry).1

In this work, Schiller categorized poets into two groups based on their relationship to nature and their creative process:

• Naive poets: These individuals possess an immediate, intuitive connection to nature and reality. Their work is characterized by a spontaneous, unreflective harmony with the world, often associated with the poets of classical antiquity.21
• Sentimental poets: These writers are separated from this immediate state of nature by reflection and self-consciousness. They strive to regain that lost harmony through intellectual effort and critical awareness, a process that defines much of modern literature.21

Schiller considered Goethe a "naive" poet because he perceived in Goethe’s work an effortless, objective mastery and a direct, harmonious engagement with the world that mirrored the qualities of the ancients, contrasting with Schiller’s own more reflective, "sentimental" approach.1