Judging by the Traffic version of the lyrics, (which is what we're discussing here) and the tone of their song, the inflection and overall mood of the song. I feel they are expressing their fear and obsession of alcohol. Where barley is almost worshiped and cultivated in our lives, yet has a dark side, almost tyrannical effect on our lives. Just like getting drunk, we start out happy and joyous, only to be depressed, drunken, and sick. No matter how much you enjoy drinking, anyone who has done it for more than a little time has to admit that sooner or later the oppressive factor in drinking catches up with you.

I love the drink. I miss the drink. Yet I'm better off without it.

After the first drink all bets are off, John Barleycorn has taken over:

"And little Sir John and the nut brown bowl proved the strongest man at last
The huntsman he can't hunt the fox nor so loudly to blow his horn
And the tinker he can't mend kettle or pots without a little barleycorn"

Love On Ya All