In the Samkhyan universe, Purusha (consciousness) and Prakriti (energy) meet in every moment (kshaNa) and manifest creation (kAla, prANa and avidyA).  This in turn has aspects which are gross - vyakta and vishesha and those that are subtle - avyakta and avishesha.  

So for example, when we feel joy it is expressed on our faces as a smile, in our heart as space and in our being as freedom.  Music too is an expression of the energy which is being created in every kshaNa. It may be expressed in words which convey specific emotions while also shining the light on the inner crevices of the mind and heart, which are more subtle.  

The Dagarbani tradition of Dhrupad leans more towards expression as AlAp.  Instead of words, syllables are used from a Sanskrit mantra - Om anantahari nArayana tarana tArini tOm.  The filigree created by various tempos allow the musician to dialogue with the rAga and explore its emotive possibilities.  In turn, this systematic unfolding of the rAga creates an evocative progression in the listener’s mind.