Your son came from an invisible quarter. He has gone away and become invisible. He did not know you. You did not know him. Who are you and for whom do you grieve.
अदर्शनादापतितः पुनश्चादर्शनं गतः। न त्वासौ वेद न त्वं तं कः सन् किमनुशोचसि॥