 The appearance of Lenard was originally suggested by Gene Roddenberry as an alternative to an appearance by Leonard Nimoy , as it was suspected that it would be too expensive to have the latter actor reprise the role of Spock on television . Roddenberry had previously barred references to Star Trek : The Original Series in The Next Generation ; the inclusion of Sarek in his namesake episode , along with a mention of Spock , was seen by the crew of The Next Generation as a breakthrough , allowing them to reference The Original Series more freely in the future . Sarek 's failing health was intended to be a reference to the declining health of Roddenberry . " Sarek " received Nielsen ratings of 10 @.@ 6 percent ; it was praised by critics , who lauded the performances of both Lenard and Stewart . 
