Personal Development for Smart People, by Steve Pavlina.
It lists the three core principles of personal development as Truth, Love and Power.
When you combine the principles, you get the secondary principles of personal development; Truth combined with Love gives you Oneness, Love and Power combine to give you Courage and Truth with Power gives you Authority. All together, the six principles combine to give you the seventh core principle of personal development: Intelligence.
Truth + Love = Oneness
Love + Power = Courage
Truth + Power = Authority
Truth + Love + Power + Oneness + Courage + Authority = INTELLIGENCE!
This kinda make sense to me.
P/S : Just some random thing I'd love to share. =)