Complex sentence: The question of what the conditions are that must be met for something to really qualify as "knowledge" is as old as philosophy itself, and is a constant theme of Plato's dialogues, notably "Meno" (97a--98b).
Split into simpler sentences: The question of what conditions need to me met to constitute "knowledge" is as old as philosophy itself. Its earliest instances are found in Plato's dialogues, notably "Meno" (97a--98b).