Passing thoughts .. why ?

I am really at a loss to understand why certain thoughts

invades me for no known reason.  Today while I was sitting

on the balcony of my son's flat in Hyderabad I was suddenly 

overpowered by such bizarre thoughts. Bizzare in the sense

that there was no immediate situation that could provoke such

unimaginable sense of emotion. However it prevailed and I was

simply carried along with the waves that beckoned- further and

further-away from the realities of the present world.

I thought  but failed to connect myself - wonder why ?

 I suddenly remembered a Tagore song sung by Babul Supriyo

while casually watching the TV. 'Tumi kon kanoner ful   Kon

gogoner tara' The song engulfed me completely and kept on

and on reverberating within me with a strange consistency.

Being a musician myself with sufficient knowledge of Indian

Classical Music as well as Rabindrasangeet I failed to come to

 a reasonable conclusion to my predicament.

Why such thoughts ..why ? Is it connected to my childhood days?