Final Answer:
Symphony No. 1 started out as a(n) orchestral fantasy and became a(n) full-fledged symphony.
Step-by-step explanation:
Orchestral Fantasy: The term "orchestral fantasy" suggests an initial phase of the composition that might have been more exploratory or experimental, with a focus on orchestral elements.
Full-Fledged Symphony: The transformation into a "full-fledged symphony" indicates that the composer developed the initial orchestral fantasy into a complete and structured symphonic work. This progression often involves refining themes, orchestrations, and overall structure to create a cohesive symphonic composition.
Understanding the evolution of a musical piece from its conceptual stage to a fully realized symphony provides insight into the creative process of the composer.