A personal favorite and semi-sequel to D.C. Fontana's other favorite effort - the original series episode Journey to Babel, this episode follows Spock back in time to his childhood and reveals some of his trials and tribulations as a half-human/half-vulcan child on a world that enforces ritual and conformity.
This poignant story was the one submitted for Emmy consideration and it won the show a daytime Emmy for Best Children's Programming. In its short running time, we meet I-Chiya, the fearsome yet lovable and loyal sehlat that Spock had as a pet, who saves young Spock's life during an ordeal involving a deadly creature in the Vulcan desert while going through a manhood ritual known as the Kas-wan. Yet Spock's earlier travel through time for research using the Guardian of Forever, had altered that history, where his young self ends up dying during the ritual. And this change not only wipes any knowledge of Spock's existence out of the current time that he returns to, but results in the non-aligned Andorians suddenly appearing as members of the Federation among other major changes discovered during the current time. So he must go back in time once more to fix what changed, saving his own life and restoring the proper timeline. But doing so comes at the cost of his young self going through the heart-breaking experience (at least for his human side) of watching his pet sehlat die after saving him. This particular outcome of showing the death of a child's pet during the Saturday morning cartoons, was considered controversial at the time, but was allowed to air (and was most likely the first time such did).
It was nice to see Sarek and Amanda again and to learn Amanda's maiden name. It was also nice to actually see the Kas-wan ritual played out, as it was an important milestone for a young Vulcan as he begins to mature, and mention of it would come later in both Voyager and Enterprise.
There was alot packed into the episode and it was and continues to be deserving of its many accolades and outstanding rating.