You could approach this from a number of angles. At its simplest the episode heightens the drama of what is probably the most dramatic book in the Aeneid. It is a scene of great power and graphic imagery, very swift and chilling in its execution and extremely affecting, even for the modern reader. However, I have always viewed the episode from a psychological perspective. At this point the Trojans are experiencing very mixed emotions. They are exultant at the apparent departure of the Greeks but also still fearful and divided about how to take in the story that the devious Sinon has been telling them about the gift horse. Then Laocoon appears dramatically on the scene. He has been selected by lot to act as priest to Neptune, a fact that can only add to the Trojans' confusion because of the past history of Neptune in relation to Troy's foundation and perhaps also because of Neptune's connection with horses. When Laocoon physically assaults the wooden horse with the spear, we might well feel we have reached the height of drama and tension but then the snakes appear and, within seconds it seems, Laocoon and his sons are destroyed. This is what drives the message home to the Trojans: now at last one thing at least seems clear, namely that the gods are punishing the one man who has dared not to just to challenge Sinon's story but to desecrate the gift which the Greeks have left. When the snakes finally slither under the statue of Pallas, Troy's protectress, the psychological impact is driven further home. The Trojans' relief at knowing at last how to act is then emphasised by the triumphal and joyous manner in which they drag the horse into the city, unaware that Neptune's revenge is about to be completed.