Theory:

Meanings of difficult words in the poem "Making life worthwhile":
 
No.
Words
Meanings
1
slightestsmall in degree; inconsiderable.
2
gracesmoothness and elegance of movement.
3
kindlyin a warm-hearted, gentle manner.
4
aspirationa hope or ambition of achieving some desire, wish.
5
darkening become unhappy or gloomy.
6
gleamshine with brightness.
7
thickeningthe process of becoming broader, more dense/deep.
8
ills
problem or misfortune.
9
glimpsea quick look or glance.
10
worthwhilevaluable, with purpose.
11
surermake sure, definite.
12
heritagea special possession, inheritance.