Learn Spanish (Latin America): El aislarse durante el ritual místico purifica el organismo. - Isolating oneself during the mystical ritual purifies the organism.

In Spanish, you can place the masculine singular article el before an infinitive to turn it into a noun phrase that acts as the subject of the sentence. This is called an articulated infinitive. In English, this usually translates to an '-ing' word, like 'isolating'.

Could I drop the El and just start the sentence with Aislarse?

Yes, using a bare infinitive as a subject is perfectly correct and very common. Adding el just gives the subject a bit more formal or conceptual weight, making it sound similar to saying 'the act of isolating oneself'.

Why is the pronoun se attached to the end of aislarse?

Because aislar is in its infinitive form here. In Spanish, reflexive and object pronouns must be attached directly to the end of infinitives, gerunds, and affirmative commands. It is reflexive because the unstated subject is isolating themselves, rather than isolating someone or something else.

How do we know to conjugate purifica in the third-person singular?

The subject of the verb purifica is the entire phrase El aislarse durante el ritual místico. Whenever an infinitive or an articulated infinitive acts as the subject of a sentence, the main verb is always conjugated in the third-person singular.