All 3 Uses of

positive
in
I Know Why the Caged Bird Sings

Ever since we read The Fall of the House of Usher, we had made a pact that neither of us would allow the other to be buried without making "absolutely, positively sure" (his favorite phrase) that the person was dead.
p. 196.1 *

positively = with certainty

He seemed positively diabolic in his enjoyment of our discomfort.
p. 228.5

positively = absolutely (used for emphasis)

Translated, that meant there was nothing a person can't do, and there should be nothing a human being didn't care about. It was the most positive encouragement I could have hoped for.
p. 265.9 *

positive = optimistic

Definitions:

(1) (positive as in: I'm absolutely positive!)
certain (having no doubt; or used for emphasis)
(2) (positive as in: had a positive effect)
good or beneficial
(3) (positive as in: positive feedback from my boss)
approval or agreement
(4) (positive as in: a positive attitude)
optimistic (expecting or focusing on good things); or agreeable
(5) (positive as in: The test came back positive.)
found a condition or substance to be present
indicating the presence of something being tested for -- especially a disease, condition, or substance
(6) (positive as in: a positive number)
greater than zero (of a number)
(7) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

See a comprehensive dictionary for less common meanings of positive including some in the fields of electricity, physics, chemistry, medicine, philosophy, and grammar. Note that most all senses of positive indicate that something is good or present.