Before she published “Silent Spring,” one of the most influential books of the last century, Rachel Carson was a young aspiring poet and then a doctoral candidate in marine biology. Although she couldn’t swim and disliked boats, says historian Jill Lepore, Carson fell in love with the ocean. Gazing into tide pools, she pioneered a new kind of nature writing.  Plus: David Attenborough, the reigning master of the nature documentary, shares lessons from a life spent observing life in every corner of the world; and the cartoonist Julia Wertz, who loves the obscure nooks, crannies, and histories of New York, takes us garbage picking on a neglected bit of shoreline where the trash of decades past keeps washing ashore.