From "Nature" by Ralph Waldo Emerson: According to Emerson, how are we connected to nature, and why is that significant? Why does an adult not see nature as they did as a child?

According to Emerson's "Nature," we are all connected to nature most truly when we are alone. The "heavenly bodies," in particular, are what connect us to the sublime, because they represent something which is both continually present and also inaccessible, like God. The significance of nature to us, therefore, is that if we open our mind to it and to its beauty, we are equally opening our mind to the presence of God and of something beyond ourselves. Wise men, according to Emerson, do not "extort [Nature]'s secret" and therefore lose their curiosity about it. The wisest of us will accept that Nature's very mystery represents its closeness to God, and the fact that it can bring us closer to perfection.
This is part of why "few adult persons can see nature." Emerson indicates that only the poet, "he whose eye can integrate all the parts," can see nature as a complete landscape. Most people, in observing nature, can only appreciate superficial parts, appreciating nature through "the eye" only. By contrast, nature "shines into the eye and heart of the child." Nature is, to a child, not simply something to be looked at and experienced with the senses, but something which affects them deeply and without effort.
Emerson suggests that children have a particular "spirit of infancy" which allows them to experience the true delight of nature, whereas adults are unable to accept nature as the constant balm it can be, being too concerned with their "real sorrows." Because children have fewer sorrows and concerns, they are able to connect to nature more fully, enjoying its "cordial." Emerson regrets that others are not able to enjoy the "perfect exhilaration" of being one with nature, entering the woods and finding "perpetual youth." The woods are described as the home of God, his "plantations," in whose tranquillity a man who is open to nature can become one with it, "part or particle of God." The true joy of nature is that it "always wears the colors of the spirit," in that a man "laboring under calamity" will experience the same scene differently to another man who is happy.