Listen to the salutation to the dawn,
Look to this day for it is life, the very life of life,
In its brief course lie all the verities and realities of our existence.
The bliss of growth, the splendor of beauty,
For yesterday is but a dream and tomorrow is only a vision,
But today well spent makes every yesterday a dream of happiness and
every tomorrow a vision of hope.
Look well therefore to this day.
Such is the salutation to the dawn.
— the poet Kalidasa, from Sanskrit
Evidently, even Dale Carnegie quoted this.