[Advaita-l] When there is more then one?

[yajvan]

hariḥ oṁ
~~~~~~ 

Namasté 

We know advaita अद्वैत  means the following:   a=not + dvaita = duality , duplicity , dualism 

Also - advitīya = without a second , sole , unique, matchless ( as in couple) from a + dvitīya  a=not + dvitīya= second, couple, accompanied by, companion

So , why such a big deal over this?  What helps us better understand the value of this notion of 
this advitīya ?

IMHO there are many reasons and I  hope the members of this forum will offer their views
based upon the śāstra-s, yet one salient point for me comes from the
bṛhadaraṇyaka upaniṣad - puruṣavidha-brāhmaṇa, 2nd śloka.  It simply says the following:　　

	Any time there is a sense of 2, fear arises i.e. dvitiyad vai bhayam bhavati - 
Fear is born of duality. 

*	dvitiyad or dvitīya द्वितीय - 2nd or two , couple, 
*	bhayam or bhaya भय - fear , alarm dread apprehension 
( rooted in bhī to fear for , be anxious about ) 
*	vai an emphasis and affirmation , generally placed after a word 
and laying stress on it (it is usually translatable by 'indeed' , 
'truly' , 'certainly' )
*	bhavati or bhava भव arising or produced from , being in

praṇām