The Watchtower Society

"Furthermore, not only do we find that people cannot see the Divine Plan in studying the Bible by itself, but we see, also, that if anyone lays the Scripture Studies aside, even after he has used them, after become familiar with them, after he has read them for ten years--if he lays them aside and ignores them and goes to the Bible alone, though he has understood his Bible for ten years, our experience shows that within two years he goes into darkness.
On the other hand, if he had merely read the Scripture Studies with their references, and had not read a page of the Bible, as such, he would be in the light at the end of the two years, because he would have light of the Scriptures."

- Charles Taze Russell
The Watchtower 9/15/1910; p.298

Basically what Russell is saying is that if you study his book of references then you will really understand the Bible. But if you go and read the Bible, after you have 'understood' the Bible (meaning if you have understood it the way he does), then you will not understand the Bible. And you can only obtain the light of the Scriptures by understanding his interpretation of the Bible.

A Short History of the Watchtower Organization
An outsider listening to such claims quickly realizes, of course, that the sect has simply appropriated unto itself all the characters named in the Bible as faithful witnesses of God. By such extrapolation the denomination is able to stretch its history back to the beginnings of the human family-at least in the eyes of adherents who are willing to accept such arguments. But outside observers generally dismiss this sort of rhetoric and instead reckon the Witnesses as dating back only to Charles Taze Russell, who was born on February 16, 1852, in Pittsburgh, Pennsylvania.
Originally raised a Presbyterian, Russell was 16 years old and a member of the Congregational church in the year 1868, when he found himself losing faith. He had begun to doubt not only church creeds and doctrines, but also God and the Bible itself. At this critical juncture a chance encounter restored his faith and placed him under the influence of Second Adventist preacher Jonas Wendell.
For some years after that Russell continued to study Scripture with and under the influence of various Adventist laymen and clergy, notably Advent Christian Church minister George Stetson and the Bible Examiner's publisher George Storrs. He met locally on a regular basis with a small circle of friends to discuss the Bible, and this informal study group came to regard him as their leader or pastor.
In January, 1876, when he was 23 years old, Russell received a copy of The Herald of the Morning, an Adventist magazine published by Nelson H. Barbour of Rochester, New York. One of the distinguishing features of Barbour's group at that time was their belief that Christ returned invisibly in 1874, and this concept presented in The Herald captured Russell's attention. It meant that this Adventist splinter group had not remained defeated, as others had, when Christ failed to appear in 1874 as Adventist leaders had predicted; somehow this small group had managed to hold onto the date by affirming that the Lord had indeed returned at the appointed time, only invisibly.
Was this mere wishful thinking, coupled with a stubborn refusal to admit the error of failed chronological calculations? Perhaps, but Barbour had some arguments to offer in support of his assertions. In particular, he came up with a basis for reinterpreting the Second Coming as an invisible event: In Benjamin Wilson's Emphatic Diaglott translation of the New Testament the word rendered coming in the King James Version at Matthew 24:27, 37, 39 is translated presence instead. This served as the basis for Barbour's group to advocate, in addition to their time calculations, an invisible presence of Christ.

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"Thus the Bible is an organizational book and belongs to the Christian congregation as an organization, not to individuals, regardless of how sincerely they may believe that they can interpret the Bible.
For this reason the Bible cannot be properly understood without Jehovah's visible organization in mind."

The Watchtower 10/01/1967; p.587

"They say that it is sufficient to read the Bible exclusively, either alone or in small groups at home. But strangely, through such 'Bible reading' they have reverted right back to the apostate doctrines that commentaries by Christendom's clergy were teaching 100 years ago."

The Watchtower 08/15/1981; p 29