Does Chapter 18 support the idea of keeping a Guru's teachings secret? Please explain.

No, Chapter 18 directly refutes the idea that a Guru's teachings should be kept secret from others. The chapter dismisses this notion as 'merely imaginary and a meaningless fuss.' It argues that not only direct instructions but even spiritual guidance received in dreams should be told to all for their enlightenment. To support this point, Chapter 18 provides the example of the sage Budhakaushika, who narrated the dream-vision of the Ram Raksha initiation to everyone. This shows a clear stance that spiritual knowledge is meant for the benefit of all.