Tracy Chevalier said this quote

“ It turned out plant collecting was a solitary occupation. In the past Robert had enjoyed being alone, or so he thought. Actually he had rarely been alone for long: working in hotels, in stables, on ranches and farms, and as a miner, he had always been around others. Now, out in the woods or up in the hills or out on the flat central plain, he could go for days without speaking to anyone. His throat seemed to close up and he had to keep clearing it, singing songs aloud or reciting the Latin names of plants, just to check that he still had a voice. 'Araucaria imbricata. Sequoia sempervirens. Pinus lambertiana. Abies magnifica'. He was surprised at how much he missed people.. ”