Learn Spanish (Latin America): El náufrago empezó a alucinar por el calor. - The castaway started to hallucinate due to the heat.

In this sentence, por indicates the cause or reason for the action (due to the heat). If you used para, it would imply that the castaway hallucinated on purpose to achieve a goal, which would not make sense.

Why is there an a between empezó and alucinar?

The verb empezar requires the preposition a when it is followed by an infinitive verb. This structure (empezar a + infinitive) is a set formula used to express the start of an action.

Why is empezó in the preterite tense here instead of the imperfect?

The verb empezar (to start) pinpoints the exact moment an action began. Verbs that indicate the beginning or end of an event are typically used in the preterite during past-tense narration because they act as fixed points rather than ongoing background descriptions.

Where does the noun náufrago come from?

It is related to the verb naufragar, which means to sink or to be shipwrecked. A náufrago is a castaway or the survivor of a shipwreck. You can spot the same root used in the English word nautical.