And if (this would be a truly unrealistic haystack) the haystack were one-dimensional, so that you could only move forwards and backwards along it, your chance of success would actually be quite high, even if the direction of each step was random.
"By building understanding I think we can get away from the idea that mental illness in young people is primarily a moral problem or a random disaster and try and move understanding more toward a rational direction, " said Prof Bullmore.