Dynamics in the score tend to appear like terraces in hilly farmland. A phrase marked piano followed by a phrase of mezzo piano. There might be crescendos or diminuendos, but these might seem to be the paths from one terrace level to the next.
However, picture yourself walking along an actual terraced field. Perhaps a vineyard in Tuscany, or a rice field in Bhutan.
If you were to walk these fields, you wouldn’t find a particular terraced level to be perfectly smooth, like poured concrete. The soil would rise and fall gently, creating micro-variations in every stretch of the field.
The same has to be true of our terraced dynamics. We must understand the micro variations from note to note, from measure to measure, that make the phrase feel natural and not forced.