.emacs - minor mode behavior

[J K]

I'm just learning Emacs and have recently started working on a .emacs
file for myself.  I was hoping someone could answer what I think is
probably a simple question:

During customization of the mode line, I was able to turn on column-
number-mode with the following line in .emacs:

(setq column-number-mode t)

I understand that this line is setting 'column-number-mode to t
(true).  I also understand that this variable is created along with
the column-number-mode function by the define-minor-mode macro in
simple.el.

I then proceeded to attempt to add the time to the mode line with the
line:

(setq display-time-mode t)

This doesn't work.  I have seen that you can instead call the function
with a positive argument like so:

(display-time-mode 1)

But I don't understand why the first method doesn't work.  I think the
problem is that I don't know how emacs goes from variables being set
to t/nil to actually drawing the screen, but I was hoping to avoid
digging that deep as I still am learning.  Could someone please help
me to understand?

Also - I've read quite a few posts in this group, and it seems like
most folks lean toward using customize as opposed to hand
editing .emacs.  Am I making things harder on myself?

Thanks for the information.