Final answer:
The question about Sybil and Seymour's decision at the beach cannot be answered with the provided excerpts, as they offer various beach experiences of different characters but do not detail Sybil and Seymour's actions.
Step-by-step explanation:
The passage does not provide explicit details about the decisions made by Sybil and Seymour at the beach. Instead, it offers various fragments of different characters' interactions with the beach and the sea, creating a mosaic of seaside experiences. From having a picnic, engaging in water activities, watching plays about maritime adventures, to contemplating philosophical questions by the seaside, each excerpt alludes to a variety of beach-related choices different characters make, highlighting a broad spectrum of human experiences connected to the shore. However, the specific actions of Sybil and Seymour are not detailed within the provided texts.