After reflection, perhaps the arrangement should be:
Life truly is beautiful.
Idealists seek and nurture their own and other's growth, associated with springtime, hence the color green*. So, I thought "Life" was a fitting word to represent them.
Rationals are always seeking to discover, discern, and define eternal truth**. Studying in libraries (during wintertime) subjects such as outer space--the color blue fits them well*. So, I thought "truly" was their word.
Guardians are very practical-minded, logistical, "bringing in the sheaves" at harvest time, so their color is gold*. And, being practical, I assigned them the word "is." A good, sturdy verb, describing the present facts.
Artisans are always seeking beauty, graceful movement; as Professor Keirsey says in Brains and Careers (page 303): "Artisans are the top aesthetes, outstripping all others in the quest for good taste in matters of beauty and grace and in pleasing the senses of self and others." And their color red comes from the earlier word used to describe them, Sanguine: blood*.
*Brains and Careers, page 39
**Brains and Careers, page 238