When an artist paints a picture they want convey a specific idea or experience to the viewer, like for example the idea of wide expanse in this painting.
To share and convey this idea to the viewer an artist may perhaps sketch a first outline of the geometric shape of the earth and sky, and through continual looking at this picture they apply paint and slowly build up this spring to summer time scene they wish to share.
In asana practice we also take a specific idea, which we want to convey through the physical, geometrical form of the pose. For example, we could also take the idea of expansiveness in the practice of sitting head to knee (pascimottanasana).
And through carefully guiding the process of thinking the idea, feeling the idea and adjusting the body to move with the idea, so we begin to express a more lively quality through the physical form.
To get an example of how asana practice can be a lively, artistic activity one could look at a short video of yoga teacher Heinz Grill, consciously guiding the handstand into a lively expression of a direct, upright, clear freedom.