אמרו שנים עשר אלף זוגים תלמידים היו לו לרבי עקיבא מגבת עד אנטיפרס וכולן מתו בפרק אחד מפני שלא נהגו כבוד זה לזה והיה העולם שמם עד שבא ר"ע אצל רבותינו שבדרום ושנאה להם ר"מ ור' יהודה ור' יוסי ורבי שמעון ורבי אלעזר בן שמוע והם הם העמידו תורה אותה שעה תנא כולם מתו מפסח ועד עצרת אמר רב חמא בר אבא ואיתימא ר' חייא בר אבין כולם מתו מיתה רעה מאי היא א"ר נחמן אסכרה
They said by way of example that Rabbi Akiva had twelve thousand pairs of students in an area of land that stretched from Gevat to Antipatris in Judea, and they all died in one period of time, because they did not treat each other with respect.
And the world was desolate of Torah until Rabbi Akiva came to our Rabbis in the South and taught his Torah to them. This second group of disciples consisted of Rabbi Meir, Rabbi Yehuda, Rabbi Yosei, Rabbi Shimon, and Rabbi Elazar ben Shamua. And these are the very ones who upheld the study of Torah at that time.
It is taught that all of them died in the period from Passover until Shavuot. Rav Ḥama bar Abba said, and some say it was Rabbi Ḥiyya bar Avin: They all died a bad death. The Gemara inquires: What is it that is called a bad death? Rav Naḥman said: Diphtheria.
from the Yerushalmi it appears that they fell in the Bar-Kokhba revolt. (https://www.etzion.org.il/en/holidays/shavuot/sefirat-haomer-practices-mourning-during-sefira)
The earliest source for the custom to observe mourning practices during sefira appears in the literature of the Geonim. In "Halakhot Pesukot Min Ha-Geonim" (97) we find the following letter of Rav Natrunai Gaon:
"Regarding your question of why we do not betroth [referring to "kiddushin," which we perform today at the wedding ceremony itself] or marry in between Pesach and Shavuot: … You should know that this does not involve any actual prohibition, but rather a custom of mourning, for Chazal said that Rabbi Akiva had twelve thousand pairs of students and they all died in between Pesach and Shavuot… From that point on, the earlier generations were accustomed during these days not to marry."
(It appears from this passage that the custom emerged already during the mishnaic period- "from that point." However, we find no ancient source for these practices. See Arukh Ha-shulchan, who claims that the custom originated during the period of the Geonim.) (https://www.etzion.org.il/en/holidays/shavuot/sefirat-haomer-practices-mourning-during-sefira)
אמר להם הראשונים לא מתו אלא מפני שהיתה עיניהם צרה בתורה זה לזה אתם לא תהיו כן מיד עמדו ומלאו כל ארץ ישראל תורה
[Rabbi Akiva said to his new students:] the first students died because their eyes were narrow in the Torah they shared with each other. Do not be like this. They immediately stood up and filled the land of Israel with Torah.
Rabbi Yitzchak Hutner:
The honor (Kavod) we have for others stems from our recognition of their uniqueness.
Each human being is unique. No two individuals in the history of the world ever had the identical perception of anything. Each has his own mind, character and emotions, and each represents a unique, never to be duplicated consciousness in the cosmos. The great multitude of human beings doubtless obscures this truth, but no amount of numbers can change its validity.
"ואהבת לרעך כמוך" – רבי עקיבא אומר זה כלל גדול בתורה.
"And you shall love your neighbor as yourself" Rabbi Akiva says: This is an all-embracing principle in the Torah.
Viktor Frankl:
But there is also another aspect of experiential values. Not only experiencing something but also experiencing someone. More than that, experiencing another human being in his or her very uniqueness and it is the main attribute of a human being that he is a person in contrast to any animal he is a person. A person is always something absolutely unique irreparable in the evolution of the cosmos as is we are incomparable with any other human being and this uniqueness can be got hold of solely by a loving person, Because he not only sees the essence but also the potentials in the beloved person.
“Love is the only way to grasp another human being in the innermost core of his personality. No one can become fully aware of the very essence of another human being unless he loves him.
Each of us carries a unique spark of the divine, and each of us is also an inseparable part of the web of life.
https://judaism.stackexchange.com/questions/89129/who-has-the-right-to-come-up-with-chiddushei-torah
וְזְהִ נִקְרָא תִקּוּנֵי הַזֹּהַר, שֶׁהֵם שִׁבְעִים פָּנִים לַתּוֹרָה, שֶׁפֵּרַשׁ רַבִּי שִׁמְעוֹן בַּר יוֹחַאי בְּמִלַּת ''בְּרֵאשִׁית'' מִסִּתְרֵי תוֹרָה.
There are 70 facets to the Torah.
Rabbi Elazar of Modiin said: one who profanes sacred things, and one who despises the festivals, and one who causes his fellow’s face to blush in public, and one who annuls the covenant of our father Abraham, may he rest in peace, and he who reveals explanations in Torah which contradict the Halacha, even though he has to his credit [knowledge of the] Torah and good deeds, he has not a share in the world to come.

