For his only opera "Leonore / Fidelio", Beethoven wrote four openings in all. The so-called Opening of Leonore No. 1 is chronologically the third of the series, and was conceived in 1806-1807 for a representation of "Leonore" in Prague that did not take place. It prevailed a long time, but wrongly, like the predecessor, sidelined, of the Opening of Leonore No. 2, which was very wrong at its reception. It is therefore useful to take a look without preconceived ideas on this opening, much shorter than the numbers 2 and 3, which in its more lyrical than dramatic character, nevertheless holds its place by presenting a new light in the fight of Beethoven to the search for the ideal opening piece for his stage work. It is published here today in a study edition based on the musical text of the complete edition of Beethoven's works, with a new preface.