(Wheelock Ch. 38)
The SUPINE is a verbal noun (cf. the participle, a verbal adjective). The Supine belongs to the Fourth Declension, and is Neuter in gender. It looks amazingly (in the accusative singular) like the neuter accusative singular of the participle. In Classical Latin, it is found in only two of its cases: the accusative singular and the ablative singular. It has no plural forms at all.
Since the Supine is a noun, it can be used in a (small) variety of ways as a noun is used. As a verbal noun, it can act like a verb, in that a verb which is transitive can take a direct object in the accusative.
I. Chiefly after verbs of motion, the accusative of the supine (without a preposition) is used to indicate MOTION or to express DESIGN ('the accusative of the goal of motion'):
It urbem captum. "He goes to capture the city."
Spectatum veniunt, veniunt spectentur ut ipsae (Ovid Ars Amatoriae I. 99)
"The come to see a show; they come to be a show themselves."
Stultitia est venatum ducere invitas canes.
" Stupidity is ('consists in') leading out unwilling dogs to hunt."
Hannibal patriam defensum revocatus est.
"Hannibal was summoned back to defend his fatherland." [patriam is the object of the supine.]
II. Chiefly with adjectives, the ablative of the supine (without a preposition) is used to indicate the point-of-view from which something is seen ('the ablative of respect '). It NEVER takes an object.
Dolor erat difficilis latu.
"The pain was hard to bear."
Dictu quam re facilius est provinciam rebellatricem confecisse.
"It is easier said ('in saying') than done to subjugate completely a rebel province."
Liber erat facilis lectu.
"The book was easy to read."
III. With the assistance of the impersonal passive infinitive of the verb EO (IRI) is represented the idea which would have been expressed by the future infinitive passive (if it had existed).
Dixit urbem captum iri.
"He said that the city was going to be captured"
John Paul Adams, CSUN