The 16th of January is "Teacher's Day" in Thailand (Ācariya Pūjā) and is particularly celebrated in our tradition as Ajahn Chah's Memorial Day.
On this auspicious day, the sangha at Lokuttara would like to remember the life and teachings of Ajahn Chah, but also of Ajahn Sumedho and Ajahn Amaro, who continue to guide us to this day.
In our tradition, a teacher is considered a spiritual friend (kalyāṇa-mittatā), of whom the Buddha said to Ven. Ananda that they were "the whole of the holy life".
Additionally, the 7 qualities of a friend worth associating with are described by the Buddha as:
Piyo —lovable; endearing
Garu —estimable; respectable; venerable
Bhāvanīyo —adorable; cultured; emulable
Vattā ca—being a counsellor
Vacanakkhamo —being a patient listener
Gambhīrañca kathaṁ kattā —able to deliver deep discourses or to treat profound subjects
No caṭṭhāne niyojako —never exhorting groundlessly; not leading or spurring on to a useless end
See: AN 7.35