nechť + Verb

The particle nechť is the highly formal equivalent of the everyday particle ať. It is used to express commands, wishes, or assumptions directed at a third party or a group including the speaker (translating to 'let him/her/them' or 'let us').

Etymology:
Etymologically, nechť is a compound of the morphological imperative nech (leave/let) and the archaic emphasizing enclitic -ť. This explains why it means 'let', why it takes the indicative (the imperative is already built into the particle), and why it acts as an unbreakable clitic host.

Key Grammatical Rules:

• Position and Clitics: While nechť often starts a clause, it can perfectly well be preceded by a subject, vocative, or topicalized element (e.g., Kdo souhlasí, nechť zvedne ruku.). Regardless of its position, nechť acts as a strong clitic host, meaning any second-position clitics (like se, si, mu, ho) must attach directly after it.
• Verb Form: Despite creating an imperative meaning, nechť typically requires a 3rd-person verb (and more rarely, 1st-person plural) in the present indicative tense, never the morphological imperative. Occasionally, in highly poetic, archaic, or translated contexts, it can take a 2nd-person verb to express a direct blessing or wish (e.g., Nechť jsi šťastný! - May you be happy!). If the verb is perfective, the present form naturally conveys a future meaning (perfective present with future meaning).
• Negative Commands: To form a negative command, negate the attached verb, not the particle itself (e.g., Nechť neví levice, co činí pravice. - Let the left hand not know what the right hand is doing).
• Punctuation: Independent clauses starting with nechť that express a strong wish or command frequently end with an exclamation mark (e.g., Nechť žije král!). Conversely, when used to introduce a premise in mathematical or legal contexts, a period is standard.

Register and Usage:
This pattern is extremely formal, literary, archaic, and ceremonial. You will encounter it in:

• Legal and official texts: Nechť soud rozhodne. (Let the court decide.)
• Academic writing: Especially in mathematics and logic to introduce a premise (e.g., Nechť x je reálné číslo. - Let x be a real number).
• Ceremonial or pop culture contexts: Nechť tě provází Síla. (May the Force be with you.)
• Concessive and disjunctive clauses: In formal, academic, and older literary texts, nechť is frequently used as a concessive conjunction meaning 'even if' or 'whether... or' (e.g., Nechť prší, nebo svítí slunce... - Whether it rains or the sun shines...). In these contexts, it can also be used with the conditional mood (e.g., nechť by se stalo cokoli - whatever might happen).
• Nechťsi: Adding the particle -si gives the word a tone of indifference, defiance, or concession (e.g., Nechťsi jde. - Let him go, I don't care).

Important: Do not use nechť in everyday conversation; it will sound absurdly theatrical or stilted. For normal speech, always use ať instead.