To generate an SQL query to discover Elon Musk's tweets from 2023, I'll assume you have a table named tweets with columns username, tweet_content, and tweet_date, where tweet_date is in a format that allows filtering by year (e.g., YYYY-MM-DD). Here's the SQL query:

SELECT tweet_content
FROM tweets
WHERE username = 'ElonMusk' 
    AND tweet_date >= '2023-01-01' 
    AND tweet_date < '2024-01-01';

This query will select the tweet_content from the tweets table where the username is 'ElonMusk' and the tweet_date is within the year 2023. Adjust the table and column names according to your actual database schema.