The Buddhist Catechism was Olcott's attempt to elucidate the basic doctrines of Buddhism in an ecumenical way. This book is still in use today in Sri Lanka. Olcott is fondly remembered in Sri Lanka and by Theosophists world-wide.
Source and copyright Global Grey Ebooks: https://www.globalgreyebooks.com/index.html. The book can be downloaded from the Global Grey website.