There are two forms of the infinitive:
1a) Infinitive Construct is used as a verbal noun corresponding
to the English verbal noun ending in "-ing"
1a1) as subject
to keep the judgments
to seek thy heart
1a2) as object
in his "writing"
he spoke, "saying"
1b) The Infinitive Absolute does not allow prefixes or suffixes
1b1) Used with a verb to emphasize the verbal idea. This is often
rendered by an English adverb, such as, "surely", "utterly".
he will surely visit you
he utterly destroyed the people
1b2) It may be used by itself with the value of a finite form of
the verb, especially an imperative.
remember the sabbath day