# Note that you can use comments within
# script-files for sed!

# Search for lines that begin with the
# word "The" and save to a file called
# "old_output"

/^\<The\>/ w old_output

# Search for lines that begin with the
# word "The", substitute all occurences
# of "The" with "The particular" and save
# to a file called "new_output" 

/^\<The\>/ s/\<The\>/The particular/g w new_output