Thérèse is writing about her early experiences of the light of her vocation bursting forth in her heart, and refers to another Carmelite, Saint John of the Cross. See http://www.livres-mystiques.com/partieTEXTES/Lisieux/Histoire/fol36a53.html
The path I was walking along was so straight, so luminous, that I needed no other guide but Jesus.
When a gardener takes great care of a fruit that he wants to ripen before its season, it is never to leave it hanging on the tree, but in order to bring it to the table, beautifully served. It was something like that that Jesus had in mind when he multiplied his graces in his little flower – he who cried out during his mortal life ‘I thank thee, O Father, Lord of heaven and earth, that thou hast hid these things from the wise and prudent, and hast revealed them unto babes.’ (Luke 10: 21)
He wanted to make his mercy erupt in me; because I was little he came down to me and in secret taught me about his love. Ah! If any scholars who had passed their lives in studies had come to interrogate me, doubtless they would have been astounded to find a fourteen year old child understanding the secrets of perfection, secrets that all their science could not reveal to them because to possess them one must be poor in spirit. (Matthew 5:3)
As St John of the Cross said in his Canticle: ‘I had neither guide nor light, except the one shining in my heart. This light guided me, more surely than the light of midday, to the place where He who knew me perfectly was waiting for me.’ That place was Carmel.
(For each of them!)