To what extent should we embrace the perspectives of national identity reflected in the source? Does this relate to nationalism? I'm doing an...

That is a good quote.  It reflects a more contemporary
view of national identity than we have had in years past.  I am a United States citizen,
but I think I have a good enough acquaintanceship with Canada to comment, and I think
there are enough similarities between the countries for me to weigh in on this
topic.

In the United States, the prevailing metaphor for
immigration was the "melting pot" for many years, and I believe this was true in Canada
as well.  Society expected immigrants to assimilate as quickly as possible, and
oftentimes, the immigrants themselves were highly motivated to do so for a number of
reasons, for example, to forget the dread of what they had left behind or because there
was a considerable amount of prejudice against immigrants.  People often seemed to want
to give up their cultures.  I had a neighbor whose parents were Italian immigrants, and
my neighbor once told me that her mother refused to make any Italian dishes.  My
grandmother was Russian, but I never heard her say a word in her native tongue.  She
learned English as quickly as she could and never looked back.  So, the idea was that we
were all supposed to hop into the pot and become
Americans.

Today, the metaphor is more of a "salad bowl." 
The ingredients do not merge into one another, but maintain their individual identity. 
And I believe that in the United States and Canada, this is what immigrants are doing. 
They less frequently lose their native tongues, they are more likely to cook their
native dishes, they celebrate holidays native to their countries of origin, and keep
their links with music and literature.  I know many immigrants, and while they may
represent a statistically insignificant sampling, I do believe that they are
representative of today's climate.

If you examine the
literature of yesteryear and today, you will find that the literary representations
reflect this.  Contrast the writing of Richard Rodriguez with the immigrant experience
in The Kite Runner. I would guess that there is a body of Canadian
literature that will demonstrate this point, too.

The idea
behind the quote seems to me to be that it is fine to maintain one's ethnic identity,
but that we must also maintain a national identity, too, because if we are not all
together in the salad bowl, there will be no nation at all.