The depths of wisdom in the holy Book of the Zohar are completely enclosed behind a thousand locks, and our human language is far too lowly to formulate for us sufficiently accurate expressions in order to interpret even a single idea in this book to its fullest extent. The commentary I have composed is merely a ladder to help the reader ascend to the heights of each matter, where he can see and examine the words of the book itself. Therefore, I have found it necessary to prepare the reader and provide him with a path, a passageway, by means of reliable definitions, to enable him to discover how one should contemplate and study the book.
Who Was Baal HaSulam and Why the Zohar Needs Him
Baal HaSulam's Preface to Zohar 1:1