A successful scientist (he was elected Fellow of the Royal Society and was honoured with a knighthood), Barrett was better known for his psychical work and his attempts to reconcile it with his scientific pursuits. Certain that the human spirit could linger after bodily death, in this book Barrett examines a wide range of spiritualist practices including levitation, spirit photography, mediumship, automatic writing, the ouija board, clairvoyance, and telepathy, carefully considering the evidence for each phenomenon in the hope that they will in time be recognised as scientifically established facts. This book is a much-revised edition of Barrett's 1908 publication On the Threshold of a New World of Thought, republished to include more 'trustworthy' evidence.

    "A spiritual aspiration was the governing force of this culture", he wrote, "its core of thought, its ruling passion. Not only did it make spirituality the highest aim of life, but it even tried...to turn the whole of life towards spirituality." Sri Aurobindo held that an aggressive defence of India culture was necessary to counter the invasion of the predominantly materialistic modern Western culture. His Foundations is precisely such a defence.